Title of Invention	ROUTING OF MEDIA COMMUNICATION SERVICE
Abstract	A method of routing a request in a communication system. The method comprises searching routing information associated to an identity, and prioritizing either one of the routing information related to the identity for the first type and the routing information related to the identity of the second type. The request is then routed by using the prioritized routing information. The invention advances correct routing in a system where different identity types are available.

Title of Invention

ROUTING OF MEDIA COMMUNICATION SERVICE

Abstract

A method of routing a request in a communication system. The method comprises searching routing information associated to an identity, and prioritizing either one of the routing information related to the identity for the first type and the routing information related to the identity of the second type. The request is then routed by using the prioritized routing information. The invention advances correct routing in a system where different identity types are available.

Full Text	ROUTING OF MEDIA COMMUNICATION SERVICE FIELD OF THE INVENTION [0001] The present invention relates to telecommunication and more particularly to routing of communication messages in multimedia communication. BACKGROUND OF THE INVENTION [0002] As the telecommunication systems have evolved, services utilizing multimedia transmission have gained more and more ground. IP multimedia core network subsystem of the 3rd Generation Partnership Project (3GPP) has been designed to enable operators a standardized way to offer their subscribers multimedia services based on and built upon Internet applications, services and protocols. Smooth integration of existing services and stand-alone network elements for the standardized IP multimedia core network subsystem thus seems to present an inevitable task for most operators. [0003] For example, Push-to-talk over Cellular (PoC) service can be provided as a packet-based user or application level service in a digital communication system. In PoC, the underlying communications system provides the basic connections (i.e. IP connections) between the communications applications in the user terminals and the communication service. The PoC communication service can be provided by a communication server system while the client applications reside in the user equipment or user terminals. [0004] Owing to the significant interest for the PoC services, individual vendors have already provided early adaptations of the technology, primarily in form of stand-alone PoC systems. Quite recently a group of interested organi3 zations have prepared an industry specification for PoC, with the aim to follow existing 3rd Generation Partnership Project (3GPP) IP Multimedia Subsystem (IMS) specifications. The standardization work in this direction has since then continued in Open Mobile Alliance (OMA) using this industry specification as a starting point. [0005] However, integration of the stand-alone PoC systems to IMS systems has presented some unexpected problems. When a PoC operator wishes to integrate his stand-alone PoC system in the IMS, it would seem obvious to create an IMS subscription for all identities and subscribers of the existing PoC system, but this is, however, not the case. For example, all existing PoC users would then be obliged to upgrade their current PoC terminals into IMS capable PoC terminals and to configure the new terminals. At the time of integration the installed base of the existing system is likely to be considerable, and such extensive operations could meet a lot of resistance and cause a considerable amount of administrative work. [0006] Furthermore, it is not likely that all PoC subscribers immediately wish to become IMS subscribers. Some subscribers may be ready for direct IMS migration, but some subscribers may also wish to time the migration to a later date and to control the timing themselves. Users who do not wish to become IMS subscribers are not willing to be charged for any IMS traffic, either. However, the implementation of two kinds of IMS traffic, chargeable and nonchargeable, is not easily managed. [0007] Conventionally subscribers are categorized according to type by arranging the users' identity information into appropriate ranges. This may be implemented, for example, by configuring identities of the system so that the type of each user is easily deducible from the identity information, or by mapping the identities according to type to some other pre-categorized identity information. However, when the status of the categorizing type is not static but changes dynamically, these conventional means easily lead to complicated and conflicting definitions and implementations. [0008] For example, users of the existing PoC system that do not migrate at integration may be initially arranged to a specific addressable identity range. When they begin to show an interest in IMS services and wish to become IMS subscribers, they somehow need to be excluded from the address range. In order to manage this, the identity ranges would need to be divided which would make the management of the subscriber information very complicated. Such complexity would also affect to the critical activities based on identity information, especially the routing where the next hop is typically defined based on the identity information in the transmitted message. BRIEF DESCRIPTION OF THE INVENTION [0009] An object of the present invention is to provide a solution to prevent or eliminate problems of routing in communication systems that allow using at least two types of identities, typically including an individual identity and a ranged identity, and where the identity itself does not indicate its type. When such an identity is used for routing, interpretation of the type of identity may not be appropriate for the current purpose, and routing may actually fail or succeed depending on the ongoing activity. The objects of the invention are achieved by a method and a network element, which are characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims. [0010] The invention is based on the idea of allowing the co-existence of different types of identities and ensuring the consistency when using the identities by controllably prioritizing the routing information related to one of the identity types over the routing information related to the other identity types. The identities are advantageously publicly available for users of the communication system for requesting actions related to an entity associated with the identity. [0011] An advantage of the method and arrangement of the invention is that it improves the correct routing in a system where different identity types are available. BRIEF DESCRIPTION OF THE DRAWINGS [0012] In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which [0013] Figure 1 is a block diagram illustrating the embodied communication system of the present invention; 6 [0014] Figure 2 is a block diagram illustrating an exemplary embodiment of two interconnected PoC servers; [0015] Figure 3 illustrates a signalling flow related to the embodiment described in Figure 2; [0016] Figure 4 is a block diagram illustrating a further embodiment of two interconnected PoC servers; [0017] Figure 5 illustrates a signalling flow related to the embodiment described in Figure 4; and [0018] Figure 6 is a block diagram illustrating a functional description of a server that may be used in PoC system. DETAILED DESCRIPTION OF THE INVENTION [0019] The invention is applicable to be used in any communication system capable of providing media communication service that can be integrated to a client server environment, for example a 3GPP IP Multimedia Subsystem, a 3GPP2 Multimedia Domain (MMD) or a SIP service environment. Such systems comprise mobile communication systems as well as fixed telecommunication systems. In the following the present invention is described by means of a Push-to-talk over Cellular (PoC) media communication service in a third generation mobile communication system, without limiting the invention to this specific service or the terms used in description of the embodiment. The term service herein refers to intangible products consisting of activities between the service provider and the customer to meet the needs of the customer, covering both basic services as well as any supplementary services modifying or supplementing the underlying basic services. [0020] As illustrated in Fig 1, in the third generation (3G) mobile communications systems, a public land mobile network (PLMN) infrastructure may be logically divided into a core network (CN) 9,10,11,12 and access network (AN) infrastructures 5,6,7,8. The access network AN may be called a base station subsystem (BSS) 8 for the GSM and radio network subsystem (RNS) or radio access network (RAN) 5,6,7 for the UMTS. In the technical specifications of a third generation partnership project (3GPP), the core network CN is logically divided into a circuit-switched (CS) domain 9, a packet-switched (PS) domain 10,11 and an IP multimedia subsystem (IMS) 12. The CS domain refers to a set of all the CN entities offering "CS type of connection" for user traffic as well as all the entities supporting the related signalling. A "CS type of connection" is a connection for which dedicated network resources are allocated when a connection is established and released when the connection is released. A "PS type of connection" transfers the user information using packets so that each packet can be routed independently from the previous one. An example of the PS domain may be the GPRS .(General Packet Radio Service), and the typical entities may include a serving GPRS support node (SGSN) and a gateway GPRS support node (GGSN). The IP multimedia subsystem comprises CN elements for provision of multimedia services. The IP multimedia subsystem IMS utilizes the PS domain to transport multimedia signalling and bearer traffic. [0021] The Push-to-talk over Cellular (PoC) is an overlay speech service in a mobile cellular network. In PoC a connection between two or more parties is established typically for a long period but the actual radio channels in the air interface are activated only when somebody is talking. This corresponds to the usage of the conventional radiotelephones where the radio frequency used is agreed upon between the parties (e.g. military/police radios, LA radios) or permanently set (walkie-talkie type of radios) and whenever somebody wishes to talk she/he presses the tangent, which activates the radio transmission on the selected channel. The traditional radiotelephone services are simplex by nature, meaning that only one party (the one who is pressing the tangent) can talk at a time. [0022] More specifically, in voice communication with "push-to-talk, release- to-listen" feature, a call is based on the use of a pressel (push-to-talk switch) as a switch in a telephone: by pressing a pressel the user indicates his desire to speak, and the user equipment sends a service request to the network. Alternatively, a voice activity detector (VAD) or any suitable means can be used instead of the manual switch. The network either rejects the request or allocates the requested resources on the basis of predetermined criteria, such as the availability of resources, the priority of the requesting user, etc. At the same time, a connection is also established to a receiving user, or users when group communication is concerned. After the voice connection has been established, the requesting user may talk and the other users may listen. When the user releases the pressel or traffic inactivity occurs, such an event is detected in the network, and the resources may be released and/or the talk item may be granted to another user. [0023] In Fig. 1, as an example, a Push-to-talk Over Cellular (PoC) server system is illustrated as provided on top of the Packet Switched (PS) core network 10,11,12 in order to provide packet mode (e.g. IP) communication services to the User Equipment (UE) 1,2,3,4. A UE accessing the PS CN, and the PS core network itself, utilizes the services provided by the Radio network subsystem (RNS) or Radio access network (RAN) 5,6,7,8 to provide packetmode communication between the UE and the PS CN subsystem. The multiple access method employed in the air interface in the RAN may be Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), or any other method or a combination thereof. In the 3rd and higher generation mobile communications system the access method is primarily based on the CDMA. Further, because the traffic channels may have a wide bandwidth, corresponding to user data rates e.g. up to 2 Mbits/s, such access may also be referred as a Wideband CDMA (WCDMA). [0024] Conceptually, a packet based media communication system is provided on top of the mobile network in order to provide media communication services to the user equipment UE through the communication system. The media communication system may be embodied as a server system, and it is generally referred to as a media communication server. A communication system may comprise a plurality of media communication servers 14,15. [0025] In this embodiment the media communication servers are referred to as PoC servers, and they illustrate the combination of PoC functions that are necessary to provide the PoC service. PoC functions may be implemented in one or more separate PoC server(s) or as integrated into one or more network entities. A PoC Server is a media communication server that may be an endpoint of SIP signaling, as well as real time transport protocol (such as Realtime Transport Protocol (RTP)), and real time transport control protocol (such as Real-time Transport Control Protocol (RTCP)) signaling. The PoC Server may provide SIP session handling, policy control for access to groups, group session handling, access control, do-not-disturb (i.e. incoming session barring) functionality, floor control functionality, talker identification, participants information, quality feedback, charging reports and media distribution. A general PoC system architecture also specifies a Group and List Management Server (GLMS) which may be used in the PoC to manage groups, contact lists and access lists of the PoC users. For a person skilled in the art it is clear that the term PoC server may be interpreted to refer to a single PoC server or to a PoC system comprising a combination of a PoC server and other entities of the PoC system architecture. [0026] The block diagram of Figure 2 shows the network elements related to the currently described embodiment of the present invention. More specifically, Figure 2 shows an embodiment where two former stand-alone PoC servers PoCA 21 and PoCs 22 have been interconnected through IM subsystems IMSA 23 and IMSB 24, in order to allow the PoC communication between user equipment UEA 25 and UEe 26 to take place. PoC servers that are not inte grated with the IMS are in this context referred to as stand-alone PoC servers. For clarity, it should be noted that only essential elements for illustrating this particular embodiment of the present invention are shown in this description. For a person skilled in the art it is clear that complete communication systems comprise a plurality of elements that are not explicitly shown herein. Furthermore, in Figure 2 both PoC servers are integrated into separate IMS systems, but it is equally possible to implement the invention in configurations where the IMS is used in the originating or in the terminating end only, or where one IMS system interconnects two separate PoC servers (i.e. IMSA 23 and IMSB are the same). [0027] The IP Multimedia Core Network subsystem (IM CN subsystem), also called as IP Multimedia subsystem (IMS), comprises all core network elements for provision of multimedia services. The session flow procedures of an IMS session are controlled by a call session control function (CSCF), which is divided into several different roles. A Proxy-CSCF (P-CSCF) is substantially the first contact point within the IMS\|. The P-CSCF behaves like a proxy and thus accepts requests and services them internally or forwards them. An interrogating- CSCF (I-CSCF) is the contact point within an operator's network for all connections destined to a user of that network operator. A Serving-CSCF (S-CSCF) performs the session control services for the user equipment. It maintains a session state as required by the network operator for supporting the services. The S-CSCF usually contains a subscriber database to which required subscription data is downloaded when the user terminal registers to the S-CSCF. The operation of these call session control functions in this embodiment will be discussed below in more detail. [0028] The present embodiment illustrates a case where routing information related to the public user identity is prioritized. In the following, the embodiment is illustrated with a routing scenario where a user equipment LJEA25 sends a request addressed to a PoC identity associated with the user equipment UEe 26. The IMS session is formed by (flows of mobile originating information, information between the serving call session control functions, and mobile terminating information. The block diagram of Figure 2 describes the elements for implementing the information flows in the embodiment of the present invention. In the originating side, L)EA 25 first sends a request to a PoC server PoCA 21 of his home network. According to the embodiment of the invention, PoC subscribers are not directly IMS subscribers, but initially continue operating with their PoC user identity. On the other hand, routing between the PoC servers is managed based on IMS Public Service Identities. [0029] An IP Multi-Media Subsystem is an example of a system that comprises a variety of identities that may be associated with IP multimedia services. Firstly, every IP Multi-Media Subsystem may have one or more private user identities. The private identity is assigned by the home network operator and may be used, for example, for registration, authorisation, administration, and accounting purposes. The IP Multi-Media Subsystem may also have one or more public user identities. The public user identity/identities may be used by any use, as the IMS is capable of routing IMS messages using a public ser13 vice identity (PSI). The PSI differs from the public user identity in that it identifies a service that is hosted by an application server. Each PSI is hosted by an application server that executes the service specific logic identified by the PSI. [0030] An application server hosting the PSI may be invoked as an originating application server by modifying the filter information within the subscriber information of the users that intend to use the service identified by the PSI. The SIP requests are directed to the corresponding application server according to the originating filtering rules in the S-CSCF of the user who is using the service. Such statically pre-configured PSIs are available internally within the IMS of the operator's domain. [0031] In Figure 2 this is illustrated by means of routing information stored in Home Subscriber Servers HSSA 232 and HSSB 242 of the IMSA 23 and IMSs 24. Generally, a Home Subscriber Server is a master database, which is used for keeping a list of features and services associated with a user, and for tracking the location and means of access for its users. The HSS provides the functions of a conventional home location register, but differs from the conventional home location register in that it also communicates via IP-based interfaces and provides the functions of the user mobility server. As shown, HSSA 232 comprises routing information associated with public user identities, as well as public service identities of IMSA 23. For example, a wildcarded public service identity range PSI1A (userpoc@operA) has a routing address poc.operA because the range is hosted in the PoC server PoCA. In addition e.g. the address of the S-CSCF 234 (scscf4.operA) may be assigned to the wildcarded public service identity range PSI1A to be used in originating routing from the integrated PoC server PoCA to IMSA 23. Correspondingly HSSB 242 comprises routing information associated with public user identities and public service identities of IMSB24. For example the wildcarded public service identity range PSI1B (userpoc@operB) has the routing address poc.operB because the range is hosted in the PoC server PoCe. [0032] The request from the user equipment UEA 25 is delivered to the PoCA 21, whose address in this example is poc.operA. In the integrated environment the PoCA 21 acts as an application server (AS) and routes the request according to the originating PSI routing. Routing from the originating AS hosting the PSI can be performed in two ways. a) The AS may forward the originating request to the destination network without involving a S-CSCF. b) In case the PSI has a S-CSCF assigned, the AS may forward the originating request to this S-CSCF, which then processes the request as per regular originating S-CSCF procedures. [0033] In Figure 2 option b) is illustrated. The address of the S-CSCF may be configured in the PoCA 21 or it may be retrieved from the home subscriber server HSSA 232 of the IM subsystems IMSA 23, or some other database storage, table, list, file or the like available to the PoCA 21. In this example the scscf4.operA i.e. the S-CSCF 234 is assigned in the HSSA 232 to the public service identity PSI1A. [0034] The Serving-CSCF 234 handling the session origination performs an analysis of the destination address, and determines that it belongs to a subscriber of a different operator. The request is therefore forwarded to an entry point in the destination operator's network, the I-CSCF 244. [0035] Generally in the IMS, an application server hosting the PSI may also be invoked as a terminating application server with the PSI. The related PSIs are configured in the home network, are globally routable and can be made available to users within and outside the operator domain. [0036] A PSI can take the form of a distinct PSI (e.g. [email protected]), or of a wildcarded PSI (e.g. chatlist_ [email protected] belonging to the wildcarded PSI range chatlist_@ example.com). A range of PSIs with the same domain part in the SIP URI may be defined using a wildcard indication in the user part of the SIP-URI. There are at least two ways to route towards the AS hosting the PSI: a) The HSS maintains the assigned S-CSCF information and ISC Filter Criteria to route to the AS hosting the PSI according to IMS routing principles. In this case, the I-CSCF receives SIP requests at the terminating side, queries the HSS and directs the request to the S-CSCF assigned to the PSI. The S-CSCF forwards the session to the application server hosting the PSI according to the terminating ISC Filter Criteria. b) The HSS maintains the address information of the AS hosting the PSI. In this case, the AS address information for the PSI is returned to the ICSCF in the location query response or the like, in which case the ICSCF will forward the request directly to the AS hosting the PSI. [0037] In the embodiment of Figure 2 option b) is illustrated. The I-CSCF 244 of operator B sends a query to the home subscriber server HSSe 242 of the IM subsystem IMSB 24 to ask for a forwarding address for the request addressed to a PoC user identity user2poc@operB associated with the UEB 26. The HSSB 242 returns the AS address poc.operB assigned to the matching wildcarded public service identity range PSHe (userpoc@operB), and the ICSCF 244 using the returned AS address (poc.operB) routes the request to the PoC server PoCe 22 that then delivers the request to the user equipment [0038] Figure 3 illustrates the signaling flow information transfer related to the elements and data transfer described in the example of Figure 2. In step 3- 1 the PoC user user1poc@operA sends a request to his home PoC server poc.operA. In step 3-2 the PoC server determines a S-CSCF assigned to itself in the configuration, or assigned to the wildcarded PSI userlpoc@operA in the HSSA 232. In this example a query is made to the HSSA 232 and a matching wildcarded PSI range is found, i.e. PSI1A that is userpoc@operA with scscf4.operA assigned as an S-CSCF. In step 3-3, the PoC server sends the request to the assigned S-CSCF scscf4.operA, which forwards the request to the entry point (e.g. I-CSCF) of the IMS network where the PoC server of the user user2poc@operB is located (step 3-4). In step 3-5, the I-CSCF makes a query to the home subscriber server of the receiving user, which server maps the identity user2poc@operB to a public service identity range userpoc@operB and retrieves the name/address information (poc.operB) of the AS that hosts the wildcarded public service identity range userpoc@operB (step 3-6). The home subscriber server of the receiving user returns the address poc.operB of the home PoC server of user2poc@operB (step 3-7), and the I-CSCF routes the message to poc.operB (step 3-8). In step 3-9, the PoC server of the operator B sends the request to user2poc@operB. [0039] In the described embodiment, in the terminating routing from the PoC server to the user terminal and in the originating routing from the user terminal to the PoC server, identities of the integrated system identities or of the stand-alone PoC system can be applied. In the originating and terminating routing between the PoC servers, the IMS public service identity routing is applied. This means that routing in the integrated system can be managed without obliging the users to directly become IMS subscribers, which provides several advantages. From the terminal's point of view the existing PoC system looks the same and the users of the existing PoC system may continue to use their PoC terminals and no immediate need for changing or reconfiguring of PoC terminals is associated with the integration. Still, the routing in the network to network interface of the integrated system is harmonized according to the principles of the IMS. From the operator's point of view the arrangement allows utilization of the existing PoC server in the integrated environment and the installed base does not become obsolete when integrated. Furthermore, the operator may add new users to the integrated PoC server as the IMS users and avoid immediate investment to a new PoC server. [0040] However, a further problem is still related to the situation where former stand-alone subscribers wish to become subscribers of the IMS. In the solution described above the identities of the PoC users were grouped into one or more PSI ranges. In order to exclude a subscriber identity of a migrating subscriber from the PSI range the operator would need to divide the PSI range into separate parts. Repeating this for a number of subscribers would very quickly lead to the fragmentation of the PSI range into a plurality of PSI ranges. [0041] In a solution according to the present invention the PoC users may, however, primarily maintain their PoC subscription, be subscribed to the IMS at any moment and still avoid the division of the PSI range. This is managed by allowing the parallel existence of a wildcarded public service identity range and a public user identity belonging to that range, and consistently using the public user identity as a first search criteria. For example, a PoC user mailtoimav become a subscriber of the IMS using his PoC identity user7poc@operB as an IMS public user identity with normal public user identity routing, while the routing of the other PoC identities in the wildcarded PSI range userpoc@operB still refers to the originating/terminating PSI routing from/to the PoG server. The routing information associated with the public user identity user7poc@operB should be given precedence over the routing information associated with the public service identity user7poc@operB as a member of the wildcarded PSI range userpoc@operB. This is illustrated in Figures 4 and 5 by means of elements and related information flows in an embodiment of the present invention. [0042] The block diagram of Figure 4 shows the elements for implementing the currently described embodiment in a procedure for transmitting a request from a PoC user equipment UEA to a PoC user equipment UEe. Corresponding to Figure 2, Figure 4 shows two former stand-alone PoC servers PoCA 41 and 42 interconnected though IM subsystems IMSA 43 and IMSe 44, in order to allow PoC communication between user equipment U£A 45 and UEs 46. In Figure 4 both PoC servers are again integrated into separate IMS systems, and furthermore, some of the PoC users have also become IMS subscribers. As shown in Figure 4, the Home Subscriber Server HSSA 432 of operator A comprises routing information of the public user identity (userl poc@operA) associated with the user equipment U£A 45 and routing information of the wildcarded public service identity range (userpoc@operA) containing the public user identity as a member of the range. More specifically, the HSSA 432 comprises the address of the S-CSCF (scscfB.operA) 436 associated with the public user identity (userl poc@operA) registered by the user equipment L)EA, and application server (AS) address (poc.operA) in the filter criteria associated with this public user identity. Additionally, the HSSA 432 comprises the address of another S-CSCF of the IMSA 43 assigned to the Public service identity range PSI1A userpoc@operA. Correspondingly the HSSB442 comprises the address of the S-CSCF (scscf9.operB) 447 associated with the public user identity (user7poc@operB) registered by the user equipment UEe 46, and application server (AS) address (poc.operB) in the filter criteria associated to this public user identity. Additionally, the HSSB 442 comprises the AS address (poc.operB) to the PoC server 42 of IMSe, assigned to the Public service identity range PSHe userpoc@operB. [0043] In the embodiment of Figure 4, a user L)EA 45 sends a request that is routed to the P-CSCF 434, the first contact point within the IM CN subsystem. The P-CSCF 434 remembers from the registration procedure the CSCF for this Public user identity and routes the request to the S-CSCF 436. Based on the filter criteria downloaded from the HSSA 432, the S-CSCF 436 routes the message to a PoCA41. Routing information for forwarding the request is available to the PoCA41 in some form of a database, storage, file, table or the like. Figure 4 shows the alternative of retrieving the routing information from the HSSA 432. According to the invention, routing information may first be searched from the HSSA 432 based on the public user identity associated to the user equipment L)EA 45. Therefore, in response to the query, the HSSA 432 returns the address of the S-CSCF 436, and the PoCA41 routes the request to the S-CSCF 436. [0044] The S-CSCF 436 identifies that the request is addressed to an IMS of network B, and routes the request to an I-CSCF 446 of operator B's service area. In order to be able to route the information, the I-CSCF 446 makes a query to the HSSe of network B. According to the invention, routing information is now defined to be searched from the HSSe 442 first based on the public user identity of the receiving user equipment UEe 46. The definition may be made separately for one or more services, i.e. to be valid for the defined type of requests only. The definition may also be general, for example operatorrelated definition that is valid in the whole network. [0045] In response to the query, the HSSe 442 returns the address of a SCSCF 447 (scscf9.operB) assigned to the public user identity registered by the user equipment UEe 46. Note that in case the user of the UEs would not be an IMS subscriber, and a public user identity would not be available, the HSSe would return the AS address poc.operB assigned to the wildcarded public ser21 vice identity range PSI1B userpoc@operB. Now the I-CSCF 446, however, routes the request to the given S-CSCF 447 that evaluates the initial filter criteria of user7poc@operB and finds a match with AS address poc.operB pointing to the PoC server B. At receiving the request, the PoCB needs routing information to route the request to the receiving user UEB. Again, routing information for forwarding the request is available to the PoCB in some form of a database, storage, file, table or the like. Routing information may also be retrieved from the received request. Figure 4 shows an alternative for retrieving the routing information from the HSSB. Based on the public user identity associated with the user equipment UEB, the HSSe responds to the query by returning the SCSCF 447 address scscf9.operB assigned to the public user identity. The PoCB routes the request to the given S-CSCF 447 address. From the registration procedure, the S-CSCF 447 knows the P-CSCF 448 for the UEB, and forwards the request to it. Correspondingly, the P-CSCF 448 knows the UEB address from the registration procedure, and forwards the request to user UEB. [0046] Figure 5 illustrates the corresponding signalling flow related to the elements and data transfer described in Figure 4. In step 5-1 the PoC user UEA sends to its first contact point, the P-CSCF of IMS, a request comprising its own public user identity userl poc@operA and the public user identity user7poc@operB of user UEB. In step 5-2, the P-CSCF forwards the request to the S-CSCF of UEA, that in step 5-3 forwards, based on the filter criteria of user UEA, the request to the PoC server poc.operA of the user U£A. In step 5- 4, the PoC server poc.operA sends a query for the next routing address to the home subscriber server of the IMS of operator A. Alternatively the PoC server of user UEA may retrieve the S-CSCF address from the received request. According to the embodiment of the invention, routing information is first searched for (step 5-5) according the public user identity user1poc@operA. In step 5-6, the address scscfS.operA of the S-CSCF assigned to the public user identity user1poc@operA is returned to the PoC server of user U£A. The PoC server of user U£A forwards the message to the assigned S-CSCF (step 5-7), which determines I-CSCF of the operator of the public user identity user7poc@operB. The S-CSCF sends the request to I-CSCF (step 5-8) of operator B. In step 5-9, the I-CSCF of operator B makes a query to the home subscriber server of operator B to obtain the next hop address. According to the embodiment of the invention, the home subscriber server determines (5- 10) the routing information based on the public user identity user7poc@operB of the receiving user. The I-CSCF receives (step 5-11) the address scscf9.operB of S-CSCF assigned to the public user identity user7poc@operB of the receiving user and forwards the request (step 5-12) to it. The S-CSCF analyses/evaluates the filtering criteria associated with the public user identity user7poc@operB, and identifies the PoC server of the receiving user and forwards the request (step 5-13) to it. The PoC server of the receiving user queries (steps 5-14 and 5-15) from the home subscriber server of the receiving user the S-CSCF assigned to the public user identity user7poc@operB and delivers (step 5-16) the request to the given S-CSCF address. Alternatively the PoC server of the receiving user may retrieve the S-CSCF address from the received request. The S-CSCF determines P-CSCF of the public user identity user7poc@operB and forwards (step 5-17) the request to it. Finally, the P23 CSCF forwards (step 5-18) the request to the user equipment UEe 46 of the receiving user. [0047] Consequently, the solution according to the invention allows consistent routing for an existing service at the time of integration to the IMS. At the same time it also provides users of the existing service an easy migration to the IMS without having to divide the identity ranges for excluding the migrated users. [0048] In the examples given above the precedence of the routing information of the public user identity was implemented by prioritization of the public user when searching for the routing data, i.e. in the home subscriber server of the sending or the receiving user. The functionality was first performed by for ing the routing information based on the public user identity in the request. If such information was not found, routing information was searched for based on the public service identity. For a person skilled in the art it is clear that this is only one alternative embodiment of the invention. As regards implementation during the search, the prioritization may be implemented as an operational functionality of the database management, as described above, or the information in the database may, for example, be structured in such a manner that the information related to the public user identities are always found first before any public service identities. [0049] Alternatively, the search may be implemented both for the public user identity and for the public service identity and either of the retrieved information may be prioritized after the search. The prioritization may be imple24 mented in the database, whereby primarily the routing information of the public user identity is only provided to the querying function. Alternatively, routing information of both the public user identity and the public service identity may be forwarded to the querying function, who will then prioritize the routing information of the public user identity over the routing information of the public service identity. [0050] In terms of the network elements illustrated in Figure 2 and 4, the precedence may be implemented in any querying network entity, like in any of the call session control functions or in an application server (AS), by making sequential or parallel searches based on the separate identity types, and choosing the routing information related to the defined identity type. For example, any call state control function or the application server may submit two searches based on the public user identity and on the public service identity and prioritize the routing information received based on the public user identity. Alternatively, the precedence may be implemented in any queried network entity, like the home subscriber server, or any other database, file, storage, register or like. The queried network entity may make separate sequential or parallel searches with the identity received from the querying network entity, but return only routing information of the prioritized identity type. It is also possible to include in the query a request for routing information based on a special type of identity or based on two or more identity types. [0051] In the described embodiment routing is based on public user identities. It should be noted that the PoC facilitates also group communication, a multi-point communication service. In the IMS, groups are defined to be addressed using public service identities. One of the advantages of the present invention is that integration in the IMS does not cause changes to the addressing of the groups. Requests to and from a PoC group may be routed as a PSI routing or as Public user identity routing, for example depending on the operator's policy. Because group identities are not normally registered, they are not normal Public user identities even if the routing may be similar. [0052] In the above embodiments the public user identity was prioritized over the wildcarded public service identity range when processing the IMS requests. The prioritization order may, within the scope of protection, be defined according to the purpose, separately for one or more service applications or as a network-wide operator definition. There may be, for example, a need to use different types of user identities to collect requests primarily addressed to separate application servers to one general server. As an alternative example, let us consider a case where an operator provides a news service and maintains a general news server as 1.example. The operator also maintains separate servers for news concerning sports or politics: as4.example for political news and asT.example for sports news. The operator has defined a wildcarded PSI range news@example, according to which requests are routed to as1.example, a distinct PSI news-politics@example, according to which requests are routed to as4.example, as well as a distinct PSI newssports@ example, according to which requests are routed to as7.example. If the operator needs to route all news requests to the same general server, the operator may change the prioritization definition so that the identity in any re26 ceived news request is first searched for as wildcarded PSI identity, instead of a distinct PSI. [0053] The implementation of the described mechanisms in a network element according to the embodiment of the present invention is illustrated by referring to Figure 6. As an example, Figure 6 provides a functional description of a network element that may be used in the PoC for a call session control function (CSCF), as a PoC server, or a home subscriber server. By definition a server is a computer that serves other computers in the same or other networks by operating as the other computers request. The server of Figure 6 comprises processing means 61, an element that comprises an arithmetic logic unit, a number of special registers and control circuits. Connected to the processing means are memory means 62, a data medium where computerreadable data or programs or user data can be stored. The memory means typically comprise memory units that allow both reading and writing (RAM), and a memory whose contents can only be read (ROM). The unit also comprises an interface block 63 with input means 64 for inputting data for internal processing in the unit, and output means 65 for outputting data from the internal processes of the unit. Examples of said input means comprise a plug-in unit acting as a gateway for information delivered to its external connection points. For receiving information on the operator, the server may also comprise a keypad, or a touch screen, a microphone, or the like. Examples of said output means include a plug-in unit feeding information to the lines connected to its external connection points. For outputting information to the operator of the server, they may also comprise a screen, a touch screen, a loudspeaker, or the like. The processing means 61, memory means 62, and interface block 63 are electrically interconnected for performing systematic execution of operations on the received and/or stored data according to the predefined, essentially programmed processes of the unit. In an embodiment according to the invention, such operations comprise a functionality for implementing the operations of the call session control functions (CSCF) or of the PoC server as described above, or database management functions of a home subscriber server as described above. [0054] It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The described embodiments of the invention may be combined with each other in all possible ways. For example, the receiving user may be an IMS subscriber, while the user originating the session may not be an IMS subscriber, and vice versa. [0055] The PoC service embodied herein represents a variety of media communication services that may be integrated into a variety of packet switched communication systems, herein embodied by the IP Multimedia Subsystem. For example, the S-CSCF, P-CSCF and I-CSCF may be SIP proxies and the PoC server may be a SIP server, and the HSS may be a SIP registrar in SIP networks. Alternatively, S-CSCF, P-CSCF, I-CSCF may be servers in general networks, PoC server may be a server offering a service to users and HSS may be a user database. [0056] Furthermore, use of filter criteria, as described in the embodiment, represent one mechanism to route certain requests to specific application server(s). Any other mechanism or an address in the request may be used for routing. The invention and its embodiments are thus not limited to the examples described above but may vary within the scope of the claims. CLAIMS 1. A method of routing a request in a communication system, comprising: including in the request an identity that may be interpreted as an identity of a first type or as an identity of a second type; searching for routing information associated with the identity; prioritizing one of routing information related to the identity of the first type or routing information related to the identity of the second type; and routing the request by using the prioritized routing information. 2. The method as claimed in claim 1, comprising prioritizing one of the routing information in a network-wide operator definition. 3. The method as claimed in claim 1, comprising prioritizing one of the routing information separately for one or more services. 4. The method as claimed in claim 1, comprising: storing routing information related to at least one identity of the first type and at least one identity of the second type in a database; and prioritizing the routing information in the database. 5. The method as claimed in claim 4, comprising: arranging the search for routing information so that the prioritized routing information is always found before non-prioritized routing information. 6. The method as claimed in claim 4, comprising prioritizing the routing information by a database function. 7. The method as claimed in claim 1, comprising: querying routing information related to the identity; and prioritizing the routing information in the querying network node. 8. The method as claimed in claim 1, comprising querying nonprioritized routing information only if prioritized routing information is not available. 9. The method as claimed in claim 1, comprising: querying routing information related to the identity of a first type and to the identity of a second type; and prioritizing by choosing one of the routing information related to the identity of the first type or the routing information related to the identity of the second type. 10. A network element, comprising: storing means for storing routing information associated with an identity; searching means for searching for routing information based on an identity that may be interpreted as an identity of a first type or as an identity of a second type; prioritization means for prioritizing, one of the routing information related to the identity of the first type or the routing information related to the identity of the second type; and output means for outputting routing information, said output means being arranged to output primarily prioritized routing information. 11. The network element as claimed in claim 10, wherein said prioritization means are arranged to prioritize one of the routing information as a network-wide operator definition. 12. The network element as claimed in claim 10, wherein said prioritization means are arranged to prioritize one of the routing information separately for one or more services. 13. The network element as claimed in claim 10, wherein the storing means are arranged to store the routing information so that prioritized routing information is always found before non-prioritized routing information. 14. The network element as claimed in claim 10, further comprising: a database function arranged to choose prioritized routing information over non-prioritized routing information. 15. A network element, comprising: querying means for querying routing information for a request, said querying means being arranged to include in the query an identity that may be interpreted as an identity of a first type or as an identity of a second type; prioritization means for prioritizing one of routing information related to the identity of the first type orrouting information related to the identity of the second type; and information. routing means for routing the request according to prioritized routing 16. The network element as claimed in claim 15, wherein said querying means are arranged to query non-prioritized routing information only if prioritized routing information is not available. 17. A computer program embodied in a computer readable medium, the computer program implementing the steps of: including in a request an identity that may be interpreted as an identity of a first type or as an identity of a second type; searching for routing information associated with the identity; prioritizing one of routing information related to the identity of the first type or routing information related to the identity of the second type; and routing the request by using the prioritized routing information.

Full Text

ROUTING OF MEDIA COMMUNICATION SERVICE
FIELD OF THE INVENTION
[0001] The present invention relates to telecommunication and more particularly
to routing of communication messages in multimedia communication.
BACKGROUND OF THE INVENTION
[0002] As the telecommunication systems have evolved, services utilizing
multimedia transmission have gained more and more ground. IP multimedia
core network subsystem of the 3rd Generation Partnership Project (3GPP) has
been designed to enable operators a standardized way to offer their subscribers
multimedia services based on and built upon Internet applications, services
and protocols. Smooth integration of existing services and stand-alone network
elements for the standardized IP multimedia core network subsystem thus
seems to present an inevitable task for most operators.
[0003] For example, Push-to-talk over Cellular (PoC) service can be provided
as a packet-based user or application level service in a digital communication
system. In PoC, the underlying communications system provides the
basic connections (i.e. IP connections) between the communications applications
in the user terminals and the communication service. The PoC communication
service can be provided by a communication server system while the
client applications reside in the user equipment or user terminals.
[0004] Owing to the significant interest for the PoC services, individual vendors
have already provided early adaptations of the technology, primarily in
form of stand-alone PoC systems. Quite recently a group of interested organi3
zations have prepared an industry specification for PoC, with the aim to follow
existing 3rd Generation Partnership Project (3GPP) IP Multimedia Subsystem
(IMS) specifications. The standardization work in this direction has since then
continued in Open Mobile Alliance (OMA) using this industry specification as a
starting point.
[0005] However, integration of the stand-alone PoC systems to IMS systems
has presented some unexpected problems. When a PoC operator wishes to
integrate his stand-alone PoC system in the IMS, it would seem obvious to
create an IMS subscription for all identities and subscribers of the existing PoC
system, but this is, however, not the case. For example, all existing PoC users
would then be obliged to upgrade their current PoC terminals into IMS capable
PoC terminals and to configure the new terminals. At the time of integration the
installed base of the existing system is likely to be considerable, and such extensive
operations could meet a lot of resistance and cause a considerable
amount of administrative work.
[0006] Furthermore, it is not likely that all PoC subscribers immediately wish
to become IMS subscribers. Some subscribers may be ready for direct IMS
migration, but some subscribers may also wish to time the migration to a later
date and to control the timing themselves. Users who do not wish to become
IMS subscribers are not willing to be charged for any IMS traffic, either. However,
the implementation of two kinds of IMS traffic, chargeable and nonchargeable,
is not easily managed.
[0007] Conventionally subscribers are categorized according to type by arranging
the users' identity information into appropriate ranges. This may be
implemented, for example, by configuring identities of the system so that the
type of each user is easily deducible from the identity information, or by mapping
the identities according to type to some other pre-categorized identity information.
However, when the status of the categorizing type is not static but
changes dynamically, these conventional means easily lead to complicated
and conflicting definitions and implementations.
[0008] For example, users of the existing PoC system that do not migrate at
integration may be initially arranged to a specific addressable identity range.
When they begin to show an interest in IMS services and wish to become IMS
subscribers, they somehow need to be excluded from the address range. In
order to manage this, the identity ranges would need to be divided which
would make the management of the subscriber information very complicated.
Such complexity would also affect to the critical activities based on identity information,
especially the routing where the next hop is typically defined based
on the identity information in the transmitted message.
BRIEF DESCRIPTION OF THE INVENTION
[0009] An object of the present invention is to provide a solution to prevent
or eliminate problems of routing in communication systems that allow using at
least two types of identities, typically including an individual identity and a
ranged identity, and where the identity itself does not indicate its type. When
such an identity is used for routing, interpretation of the type of identity may not
be appropriate for the current purpose, and routing may actually fail or succeed
depending on the ongoing activity. The objects of the invention are
achieved by a method and a network element, which are characterized by
what is stated in the independent claims. The preferred embodiments of the
invention are disclosed in the dependent claims.
[0010] The invention is based on the idea of allowing the co-existence of
different types of identities and ensuring the consistency when using the identities
by controllably prioritizing the routing information related to one of the
identity types over the routing information related to the other identity types.
The identities are advantageously publicly available for users of the communication
system for requesting actions related to an entity associated with the
identity.
[0011] An advantage of the method and arrangement of the invention is
that it improves the correct routing in a system where different identity types
are available.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In the following the invention will be described in greater detail by
means of preferred embodiments with reference to the attached drawings, in
which
[0013] Figure 1 is a block diagram illustrating the embodied communication
system of the present invention;
6
[0014] Figure 2 is a block diagram illustrating an exemplary embodiment of
two interconnected PoC servers;
[0015] Figure 3 illustrates a signalling flow related to the embodiment described
in Figure 2;
[0016] Figure 4 is a block diagram illustrating a further embodiment of two
interconnected PoC servers;
[0017] Figure 5 illustrates a signalling flow related to the embodiment described
in Figure 4; and
[0018] Figure 6 is a block diagram illustrating a functional description of a
server that may be used in PoC system.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The invention is applicable to be used in any communication system
capable of providing media communication service that can be integrated to a
client server environment, for example a 3GPP IP Multimedia Subsystem, a
3GPP2 Multimedia Domain (MMD) or a SIP service environment. Such systems
comprise mobile communication systems as well as fixed telecommunication
systems. In the following the present invention is described by means of
a Push-to-talk over Cellular (PoC) media communication service in a third
generation mobile communication system, without limiting the invention to this
specific service or the terms used in description of the embodiment. The term
service herein refers to intangible products consisting of activities between the
service provider and the customer to meet the needs of the customer, covering
both basic services as well as any supplementary services modifying or supplementing
the underlying basic services.
[0020] As illustrated in Fig 1, in the third generation (3G) mobile communications
systems, a public land mobile network (PLMN) infrastructure may be
logically divided into a core network (CN) 9,10,11,12 and access network (AN)
infrastructures 5,6,7,8. The access network AN may be called a base station
subsystem (BSS) 8 for the GSM and radio network subsystem (RNS) or radio
access network (RAN) 5,6,7 for the UMTS. In the technical specifications of a
third generation partnership project (3GPP), the core network CN is logically
divided into a circuit-switched (CS) domain 9, a packet-switched (PS) domain
10,11 and an IP multimedia subsystem (IMS) 12. The CS domain refers to a
set of all the CN entities offering "CS type of connection" for user traffic as well
as all the entities supporting the related signalling. A "CS type of connection" is
a connection for which dedicated network resources are allocated when a connection
is established and released when the connection is released. A "PS
type of connection" transfers the user information using packets so that each
packet can be routed independently from the previous one. An example of the
PS domain may be the GPRS .(General Packet Radio Service), and the typical
entities may include a serving GPRS support node (SGSN) and a gateway
GPRS support node (GGSN). The IP multimedia subsystem comprises CN
elements for provision of multimedia services. The IP multimedia subsystem
IMS utilizes the PS domain to transport multimedia signalling and bearer traffic.
[0021] The Push-to-talk over Cellular (PoC) is an overlay speech service in
a mobile cellular network. In PoC a connection between two or more parties is
established typically for a long period but the actual radio channels in the air
interface are activated only when somebody is talking. This corresponds to the
usage of the conventional radiotelephones where the radio frequency used is
agreed upon between the parties (e.g. military/police radios, LA radios) or
permanently set (walkie-talkie type of radios) and whenever somebody wishes
to talk she/he presses the tangent, which activates the radio transmission on
the selected channel. The traditional radiotelephone services are simplex by
nature, meaning that only one party (the one who is pressing the tangent) can
talk at a time.
[0022] More specifically, in voice communication with "push-to-talk, release-
to-listen" feature, a call is based on the use of a pressel (push-to-talk
switch) as a switch in a telephone: by pressing a pressel the user indicates his
desire to speak, and the user equipment sends a service request to the network.
Alternatively, a voice activity detector (VAD) or any suitable means can
be used instead of the manual switch. The network either rejects the request
or allocates the requested resources on the basis of predetermined criteria,
such as the availability of resources, the priority of the requesting user, etc. At
the same time, a connection is also established to a receiving user, or users
when group communication is concerned. After the voice connection has been
established, the requesting user may talk and the other users may listen.
When the user releases the pressel or traffic inactivity occurs, such an event is
detected in the network, and the resources may be released and/or the talk
item may be granted to another user.
[0023] In Fig. 1, as an example, a Push-to-talk Over Cellular (PoC) server
system is illustrated as provided on top of the Packet Switched (PS) core network
10,11,12 in order to provide packet mode (e.g. IP) communication services
to the User Equipment (UE) 1,2,3,4. A UE accessing the PS CN, and the
PS core network itself, utilizes the services provided by the Radio network
subsystem (RNS) or Radio access network (RAN) 5,6,7,8 to provide packetmode
communication between the UE and the PS CN subsystem. The multiple
access method employed in the air interface in the RAN may be Time Division
Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Code
Division Multiple Access (CDMA), or any other method or a combination
thereof. In the 3rd and higher generation mobile communications system the
access method is primarily based on the CDMA. Further, because the traffic
channels may have a wide bandwidth, corresponding to user data rates e.g. up
to 2 Mbits/s, such access may also be referred as a Wideband CDMA
(WCDMA).
[0024] Conceptually, a packet based media communication system is provided
on top of the mobile network in order to provide media communication
services to the user equipment UE through the communication system. The
media communication system may be embodied as a server system, and it is
generally referred to as a media communication server. A communication system
may comprise a plurality of media communication servers 14,15.
[0025] In this embodiment the media communication servers are referred to
as PoC servers, and they illustrate the combination of PoC functions that are
necessary to provide the PoC service. PoC functions may be implemented in
one or more separate PoC server(s) or as integrated into one or more network
entities. A PoC Server is a media communication server that may be an endpoint
of SIP signaling, as well as real time transport protocol (such as Realtime
Transport Protocol (RTP)), and real time transport control protocol (such
as Real-time Transport Control Protocol (RTCP)) signaling. The PoC Server
may provide SIP session handling, policy control for access to groups, group
session handling, access control, do-not-disturb (i.e. incoming session barring)
functionality, floor control functionality, talker identification, participants information,
quality feedback, charging reports and media distribution. A general
PoC system architecture also specifies a Group and List Management Server
(GLMS) which may be used in the PoC to manage groups, contact lists and
access lists of the PoC users. For a person skilled in the art it is clear that the
term PoC server may be interpreted to refer to a single PoC server or to a PoC
system comprising a combination of a PoC server and other entities of the PoC
system architecture.
[0026] The block diagram of Figure 2 shows the network elements related
to the currently described embodiment of the present invention. More specifically,
Figure 2 shows an embodiment where two former stand-alone PoC servers
PoCA 21 and PoCs 22 have been interconnected through IM subsystems
IMSA 23 and IMSB 24, in order to allow the PoC communication between user
equipment UEA 25 and UEe 26 to take place. PoC servers that are not inte
grated with the IMS are in this context referred to as stand-alone PoC servers.
For clarity, it should be noted that only essential elements for illustrating this
particular embodiment of the present invention are shown in this description.
For a person skilled in the art it is clear that complete communication systems
comprise a plurality of elements that are not explicitly shown herein. Furthermore,
in Figure 2 both PoC servers are integrated into separate IMS systems,
but it is equally possible to implement the invention in configurations where the
IMS is used in the originating or in the terminating end only, or where one IMS
system interconnects two separate PoC servers (i.e. IMSA 23 and IMSB are the
same).
[0027] The IP Multimedia Core Network subsystem (IM CN subsystem),
also called as IP Multimedia subsystem (IMS), comprises all core network
elements for provision of multimedia services. The session flow procedures of
an IMS session are controlled by a call session control function (CSCF), which
is divided into several different roles. A Proxy-CSCF (P-CSCF) is substantially
the first contact point within the IMS|. The P-CSCF behaves like a proxy and
thus accepts requests and services them internally or forwards them. An interrogating-
CSCF (I-CSCF) is the contact point within an operator's network for
all connections destined to a user of that network operator. A Serving-CSCF
(S-CSCF) performs the session control services for the user equipment. It
maintains a session state as required by the network operator for supporting
the services. The S-CSCF usually contains a subscriber database to which
required subscription data is downloaded when the user terminal registers to
the S-CSCF. The operation of these call session control functions in this embodiment
will be discussed below in more detail.
[0028] The present embodiment illustrates a case where routing information
related to the public user identity is prioritized. In the following, the embodiment
is illustrated with a routing scenario where a user equipment LJEA25
sends a request addressed to a PoC identity associated with the user equipment
UEe 26. The IMS session is formed by (flows of mobile originating information,
information between the serving call session control functions, and
mobile terminating information. The block diagram of Figure 2 describes the
elements for implementing the information flows in the embodiment of the present
invention. In the originating side, L)EA 25 first sends a request to a PoC
server PoCA 21 of his home network. According to the embodiment of the invention,
PoC subscribers are not directly IMS subscribers, but initially continue
operating with their PoC user identity. On the other hand, routing between the
PoC servers is managed based on IMS Public Service Identities.
[0029] An IP Multi-Media Subsystem is an example of a system that comprises
a variety of identities that may be associated with IP multimedia services.
Firstly, every IP Multi-Media Subsystem may have one or more private
user identities. The private identity is assigned by the home network operator
and may be used, for example, for registration, authorisation, administration,
and accounting purposes. The IP Multi-Media Subsystem may also have one
or more public user identities. The public user identity/identities may be used
by any use, as the IMS is capable of routing IMS messages using a public ser13
vice identity (PSI). The PSI differs from the public user identity in that it identifies
a service that is hosted by an application server. Each PSI is hosted by an
application server that executes the service specific logic identified by the PSI.
[0030] An application server hosting the PSI may be invoked as an originating
application server by modifying the filter information within the subscriber
information of the users that intend to use the service identified by the
PSI. The SIP requests are directed to the corresponding application server
according to the originating filtering rules in the S-CSCF of the user who is using
the service. Such statically pre-configured PSIs are available internally
within the IMS of the operator's domain.
[0031] In Figure 2 this is illustrated by means of routing information stored
in Home Subscriber Servers HSSA 232 and HSSB 242 of the IMSA 23 and
IMSs 24. Generally, a Home Subscriber Server is a master database, which is
used for keeping a list of features and services associated with a user, and for
tracking the location and means of access for its users. The HSS provides the
functions of a conventional home location register, but differs from the conventional
home location register in that it also communicates via IP-based interfaces
and provides the functions of the user mobility server. As shown, HSSA
232 comprises routing information associated with public user identities, as
well as public service identities of IMSA 23. For example, a wildcarded public
service identity range PSI1A (user*poc@operA) has a routing address
poc.operA because the range is hosted in the PoC server PoCA. In addition
e.g. the address of the S-CSCF 234 (scscf4.operA) may be assigned to the
wildcarded public service identity range PSI1A to be used in originating routing
from the integrated PoC server PoCA to IMSA 23. Correspondingly HSSB 242
comprises routing information associated with public user identities and public
service identities of IMSB24. For example the wildcarded public service identity
range PSI1B (user*poc@operB) has the routing address poc.operB because
the range is hosted in the PoC server PoCe.
[0032] The request from the user equipment UEA 25 is delivered to the
PoCA 21, whose address in this example is poc.operA. In the integrated environment
the PoCA 21 acts as an application server (AS) and routes the request
according to the originating PSI routing. Routing from the originating AS hosting
the PSI can be performed in two ways.
a) The AS may forward the originating request to the destination network
without involving a S-CSCF.
b) In case the PSI has a S-CSCF assigned, the AS may forward the originating
request to this S-CSCF, which then processes the request as per
regular originating S-CSCF procedures.
[0033] In Figure 2 option b) is illustrated. The address of the S-CSCF may
be configured in the PoCA 21 or it may be retrieved from the home subscriber
server HSSA 232 of the IM subsystems IMSA 23, or some other database storage,
table, list, file or the like available to the PoCA 21. In this example the
scscf4.operA i.e. the S-CSCF 234 is assigned in the HSSA 232 to the public
service identity PSI1A.
[0034] The Serving-CSCF 234 handling the session origination performs
an analysis of the destination address, and determines that it belongs to a
subscriber of a different operator. The request is therefore forwarded to an entry
point in the destination operator's network, the I-CSCF 244.
[0035] Generally in the IMS, an application server hosting the PSI may also
be invoked as a terminating application server with the PSI. The related PSIs
are configured in the home network, are globally routable and can be made
available to users within and outside the operator domain.
[0036] A PSI can take the form of a distinct PSI (e.g.
[email protected]), or of a wildcarded PSI (e.g. chatlist_
[email protected] belonging to the wildcarded PSI range chatlist_*@
example.com). A range of PSIs with the same domain part in the SIP
URI may be defined using a wildcard indication in the user part of the SIP-URI.
There are at least two ways to route towards the AS hosting the PSI:
a) The HSS maintains the assigned S-CSCF information and ISC Filter Criteria
to route to the AS hosting the PSI according to IMS routing principles.
In this case, the I-CSCF receives SIP requests at the terminating
side, queries the HSS and directs the request to the S-CSCF assigned to
the PSI. The S-CSCF forwards the session to the application server hosting
the PSI according to the terminating ISC Filter Criteria.
b) The HSS maintains the address information of the AS hosting the PSI. In
this case, the AS address information for the PSI is returned to the ICSCF
in the location query response or the like, in which case the ICSCF
will forward the request directly to the AS hosting the PSI.
[0037] In the embodiment of Figure 2 option b) is illustrated. The I-CSCF
244 of operator B sends a query to the home subscriber server HSSe 242 of
the IM subsystem IMSB 24 to ask for a forwarding address for the request addressed
to a PoC user identity user2poc@operB associated with the UEB 26.
The HSSB 242 returns the AS address poc.operB assigned to the matching
wildcarded public service identity range PSHe (user*poc@operB), and the ICSCF
244 using the returned AS address (poc.operB) routes the request to
the PoC server PoCe 22 that then delivers the request to the user equipment
[0038] Figure 3 illustrates the signaling flow information transfer related to
the elements and data transfer described in the example of Figure 2. In step 3-
1 the PoC user user1poc@operA sends a request to his home PoC server
poc.operA. In step 3-2 the PoC server determines a S-CSCF assigned to itself
in the configuration, or assigned to the wildcarded PSI userlpoc@operA in the
HSSA 232. In this example a query is made to the HSSA 232 and a matching
wildcarded PSI range is found, i.e. PSI1A that is user*poc@operA with
scscf4.operA assigned as an S-CSCF. In step 3-3, the PoC server sends the
request to the assigned S-CSCF scscf4.operA, which forwards the request to
the entry point (e.g. I-CSCF) of the IMS network where the PoC server of the
user user2poc@operB is located (step 3-4). In step 3-5, the I-CSCF makes a
query to the home subscriber server of the receiving user, which server maps
the identity user2poc@operB to a public service identity range
user*poc@operB and retrieves the name/address information (poc.operB) of
the AS that hosts the wildcarded public service identity range user*poc@operB
(step 3-6). The home subscriber server of the receiving user returns the address
poc.operB of the home PoC server of user2poc@operB (step 3-7), and
the I-CSCF routes the message to poc.operB (step 3-8). In step 3-9, the PoC
server of the operator B sends the request to user2poc@operB.
[0039] In the described embodiment, in the terminating routing from the
PoC server to the user terminal and in the originating routing from the user terminal
to the PoC server, identities of the integrated system identities or of the
stand-alone PoC system can be applied. In the originating and terminating
routing between the PoC servers, the IMS public service identity routing is applied.
This means that routing in the integrated system can be managed without
obliging the users to directly become IMS subscribers, which provides several
advantages. From the terminal's point of view the existing PoC system
looks the same and the users of the existing PoC system may continue to use
their PoC terminals and no immediate need for changing or reconfiguring of
PoC terminals is associated with the integration. Still, the routing in the network
to network interface of the integrated system is harmonized according to the
principles of the IMS. From the operator's point of view the arrangement allows
utilization of the existing PoC server in the integrated environment and the installed
base does not become obsolete when integrated. Furthermore, the operator
may add new users to the integrated PoC server as the IMS users and
avoid immediate investment to a new PoC server.
[0040] However, a further problem is still related to the situation where former
stand-alone subscribers wish to become subscribers of the IMS. In the
solution described above the identities of the PoC users were grouped into one
or more PSI ranges. In order to exclude a subscriber identity of a migrating
subscriber from the PSI range the operator would need to divide the PSI range
into separate parts. Repeating this for a number of subscribers would very
quickly lead to the fragmentation of the PSI range into a plurality of PSI
ranges.
[0041] In a solution according to the present invention the PoC users may,
however, primarily maintain their PoC subscription, be subscribed to the IMS at
any moment and still avoid the division of the PSI range. This is managed by
allowing the parallel existence of a wildcarded public service identity range and
a public user identity belonging to that range, and consistently using the public
user identity as a first search criteria. For example, a PoC user mailtoimav become
a subscriber of the IMS using his PoC identity user7poc@operB as an
IMS public user identity with normal public user identity routing, while the routing
of the other PoC identities in the wildcarded PSI range user*poc@operB
still refers to the originating/terminating PSI routing from/to the PoG server.
The routing information associated with the public user identity
user7poc@operB should be given precedence over the routing information
associated with the public service identity user7poc@operB as a member of
the wildcarded PSI range user*poc@operB. This is illustrated in Figures 4 and
5 by means of elements and related information flows in an embodiment of
the present invention.
[0042] The block diagram of Figure 4 shows the elements for implementing
the currently described embodiment in a procedure for transmitting a request
from a PoC user equipment UEA to a PoC user equipment UEe. Corresponding
to Figure 2, Figure 4 shows two former stand-alone PoC servers PoCA 41 and
42 interconnected though IM subsystems IMSA 43 and IMSe 44, in order
to allow PoC communication between user equipment U£A 45 and UEs 46. In
Figure 4 both PoC servers are again integrated into separate IMS systems,
and furthermore, some of the PoC users have also become IMS subscribers.
As shown in Figure 4, the Home Subscriber Server HSSA 432 of operator A
comprises routing information of the public user identity (userl poc@operA)
associated with the user equipment U£A 45 and routing information of the
wildcarded public service identity range (user*poc@operA) containing the public
user identity as a member of the range. More specifically, the HSSA 432
comprises the address of the S-CSCF (scscfB.operA) 436 associated with the
public user identity (userl poc@operA) registered by the user equipment L)EA,
and application server (AS) address (poc.operA) in the filter criteria associated
with this public user identity. Additionally, the HSSA 432 comprises the address
of another S-CSCF of the IMSA 43 assigned to the Public service identity
range PSI1A user*poc@operA. Correspondingly the HSSB442 comprises the
address of the S-CSCF (scscf9.operB) 447 associated with the public user
identity (user7poc@operB) registered by the user equipment UEe 46, and application
server (AS) address (poc.operB) in the filter criteria associated to this
public user identity. Additionally, the HSSB 442 comprises the AS address
(poc.operB) to the PoC server 42 of IMSe, assigned to the Public service identity
range PSHe user*poc@operB.
[0043] In the embodiment of Figure 4, a user L)EA 45 sends a request that
is routed to the P-CSCF 434, the first contact point within the IM CN subsystem.
The P-CSCF 434 remembers from the registration procedure the CSCF
for this Public user identity and routes the request to the S-CSCF 436. Based
on the filter criteria downloaded from the HSSA 432, the S-CSCF 436 routes
the message to a PoCA41. Routing information for forwarding the request is
available to the PoCA41 in some form of a database, storage, file, table or the
like. Figure 4 shows the alternative of retrieving the routing information from
the HSSA 432. According to the invention, routing information may first be
searched from the HSSA 432 based on the public user identity associated to
the user equipment L)EA 45. Therefore, in response to the query, the HSSA 432
returns the address of the S-CSCF 436, and the PoCA41 routes the request to
the S-CSCF 436.
[0044] The S-CSCF 436 identifies that the request is addressed to an IMS
of network B, and routes the request to an I-CSCF 446 of operator B's service
area. In order to be able to route the information, the I-CSCF 446 makes a
query to the HSSe of network B. According to the invention, routing information
is now defined to be searched from the HSSe 442 first based on the public
user identity of the receiving user equipment UEe 46. The definition may be
made separately for one or more services, i.e. to be valid for the defined type
of requests only. The definition may also be general, for example operatorrelated
definition that is valid in the whole network.
[0045] In response to the query, the HSSe 442 returns the address of a SCSCF
447 (scscf9.operB) assigned to the public user identity registered by the
user equipment UEe 46. Note that in case the user of the UEs would not be an
IMS subscriber, and a public user identity would not be available, the HSSe
would return the AS address poc.operB assigned to the wildcarded public ser21
vice identity range PSI1B user*poc@operB. Now the I-CSCF 446, however,
routes the request to the given S-CSCF 447 that evaluates the initial filter criteria
of user7poc@operB and finds a match with AS address poc.operB pointing
to the PoC server B. At receiving the request, the PoCB needs routing information
to route the request to the receiving user UEB. Again, routing information
for forwarding the request is available to the PoCB in some form of a database,
storage, file, table or the like. Routing information may also be retrieved from
the received request. Figure 4 shows an alternative for retrieving the routing
information from the HSSB. Based on the public user identity associated with
the user equipment UEB, the HSSe responds to the query by returning the SCSCF
447 address scscf9.operB assigned to the public user identity. The
PoCB routes the request to the given S-CSCF 447 address. From the registration
procedure, the S-CSCF 447 knows the P-CSCF 448 for the UEB, and forwards
the request to it. Correspondingly, the P-CSCF 448 knows the UEB address
from the registration procedure, and forwards the request to user UEB.
[0046] Figure 5 illustrates the corresponding signalling flow related to the
elements and data transfer described in Figure 4. In step 5-1 the PoC user
UEA sends to its first contact point, the P-CSCF of IMS, a request comprising
its own public user identity userl poc@operA and the public user identity
user7poc@operB of user UEB. In step 5-2, the P-CSCF forwards the request
to the S-CSCF of UEA, that in step 5-3 forwards, based on the filter criteria of
user UEA, the request to the PoC server poc.operA of the user U£A. In step 5-
4, the PoC server poc.operA sends a query for the next routing address to the
home subscriber server of the IMS of operator A. Alternatively the PoC server
of user UEA may retrieve the S-CSCF address from the received request. According
to the embodiment of the invention, routing information is first
searched for (step 5-5) according the public user identity user1poc@operA. In
step 5-6, the address scscfS.operA of the S-CSCF assigned to the public user
identity user1poc@operA is returned to the PoC server of user U£A. The
PoC server of user U£A forwards the message to the assigned S-CSCF (step
5-7), which determines I-CSCF of the operator of the public user identity
user7poc@operB. The S-CSCF sends the request to I-CSCF (step 5-8) of operator
B. In step 5-9, the I-CSCF of operator B makes a query to the home
subscriber server of operator B to obtain the next hop address. According to
the embodiment of the invention, the home subscriber server determines (5-
10) the routing information based on the public user identity user7poc@operB
of the receiving user. The I-CSCF receives (step 5-11) the address
scscf9.operB of S-CSCF assigned to the public user identity user7poc@operB
of the receiving user and forwards the request (step 5-12) to it. The S-CSCF
analyses/evaluates the filtering criteria associated with the public user identity
user7poc@operB, and identifies the PoC server of the receiving user and forwards
the request (step 5-13) to it. The PoC server of the receiving user queries
(steps 5-14 and 5-15) from the home subscriber server of the receiving
user the S-CSCF assigned to the public user identity user7poc@operB and
delivers (step 5-16) the request to the given S-CSCF address. Alternatively the
PoC server of the receiving user may retrieve the S-CSCF address from the
received request. The S-CSCF determines P-CSCF of the public user identity
user7poc@operB and forwards (step 5-17) the request to it. Finally, the P23
CSCF forwards (step 5-18) the request to the user equipment UEe 46 of the
receiving user.
[0047] Consequently, the solution according to the invention allows consistent
routing for an existing service at the time of integration to the IMS. At the
same time it also provides users of the existing service an easy migration to
the IMS without having to divide the identity ranges for excluding the migrated
users.
[0048] In the examples given above the precedence of the routing information
of the public user identity was implemented by prioritization of the public
user when searching for the routing data, i.e. in the home subscriber server of
the sending or the receiving user. The functionality was first performed by for
ing the routing information based on the public user identity in the request. If
such information was not found, routing information was searched for based
on the public service identity. For a person skilled in the art it is clear that this
is only one alternative embodiment of the invention. As regards implementation
during the search, the prioritization may be implemented as an operational
functionality of the database management, as described above, or the information
in the database may, for example, be structured in such a manner that the
information related to the public user identities are always found first before
any public service identities.
[0049] Alternatively, the search may be implemented both for the public
user identity and for the public service identity and either of the retrieved information
may be prioritized after the search. The prioritization may be imple24
mented in the database, whereby primarily the routing information of the public
user identity is only provided to the querying function. Alternatively, routing information
of both the public user identity and the public service identity may be
forwarded to the querying function, who will then prioritize the routing information
of the public user identity over the routing information of the public service
identity.
[0050] In terms of the network elements illustrated in Figure 2 and 4, the
precedence may be implemented in any querying network entity, like in any of
the call session control functions or in an application server (AS), by making
sequential or parallel searches based on the separate identity types, and
choosing the routing information related to the defined identity type. For example,
any call state control function or the application server may submit two
searches based on the public user identity and on the public service identity
and prioritize the routing information received based on the public user identity.
Alternatively, the precedence may be implemented in any queried network entity,
like the home subscriber server, or any other database, file, storage, register
or like. The queried network entity may make separate sequential or parallel
searches with the identity received from the querying network entity, but
return only routing information of the prioritized identity type. It is also possible
to include in the query a request for routing information based on a special
type of identity or based on two or more identity types.
[0051] In the described embodiment routing is based on public user identities.
It should be noted that the PoC facilitates also group communication, a
multi-point communication service. In the IMS, groups are defined to be addressed
using public service identities. One of the advantages of the present
invention is that integration in the IMS does not cause changes to the addressing
of the groups. Requests to and from a PoC group may be routed as a PSI
routing or as Public user identity routing, for example depending on the operator's
policy. Because group identities are not normally registered, they are not
normal Public user identities even if the routing may be similar.
[0052] In the above embodiments the public user identity was prioritized
over the wildcarded public service identity range when processing the IMS requests.
The prioritization order may, within the scope of protection, be defined
according to the purpose, separately for one or more service applications or as
a network-wide operator definition. There may be, for example, a need to use
different types of user identities to collect requests primarily addressed to
separate application servers to one general server. As an alternative example,
let us consider a case where an operator provides a news service and maintains
a general news server as 1.example. The operator also maintains separate
servers for news concerning sports or politics: as4.example for political
news and asT.example for sports news. The operator has defined a wildcarded
PSI range news*@example, according to which requests are routed to
as1.example, a distinct PSI news-politics@example, according to which requests
are routed to as4.example, as well as a distinct PSI newssports@
example, according to which requests are routed to as7.example. If
the operator needs to route all news requests to the same general server, the
operator may change the prioritization definition so that the identity in any re26
ceived news request is first searched for as wildcarded PSI identity, instead of
a distinct PSI.
[0053] The implementation of the described mechanisms in a network element
according to the embodiment of the present invention is illustrated by
referring to Figure 6. As an example, Figure 6 provides a functional description
of a network element that may be used in the PoC for a call session control
function (CSCF), as a PoC server, or a home subscriber server. By definition a
server is a computer that serves other computers in the same or other networks
by operating as the other computers request. The server of Figure 6
comprises processing means 61, an element that comprises an arithmetic logic
unit, a number of special registers and control circuits. Connected to the processing
means are memory means 62, a data medium where computerreadable
data or programs or user data can be stored. The memory means
typically comprise memory units that allow both reading and writing (RAM),
and a memory whose contents can only be read (ROM). The unit also comprises
an interface block 63 with input means 64 for inputting data for internal
processing in the unit, and output means 65 for outputting data from the internal
processes of the unit. Examples of said input means comprise a plug-in
unit acting as a gateway for information delivered to its external connection
points. For receiving information on the operator, the server may also comprise
a keypad, or a touch screen, a microphone, or the like. Examples of said output
means include a plug-in unit feeding information to the lines connected to
its external connection points. For outputting information to the operator of the
server, they may also comprise a screen, a touch screen, a loudspeaker, or
the like. The processing means 61, memory means 62, and interface block 63
are electrically interconnected for performing systematic execution of operations
on the received and/or stored data according to the predefined, essentially
programmed processes of the unit. In an embodiment according to the
invention, such operations comprise a functionality for implementing the operations
of the call session control functions (CSCF) or of the PoC server as described
above, or database management functions of a home subscriber
server as described above.
[0054] It will be obvious to a person skilled in the art that, as technology
advances, the inventive concept can be implemented in various ways. The described
embodiments of the invention may be combined with each other in all
possible ways. For example, the receiving user may be an IMS subscriber,
while the user originating the session may not be an IMS subscriber, and vice
versa.
[0055] The PoC service embodied herein represents a variety of media
communication services that may be integrated into a variety of packet
switched communication systems, herein embodied by the IP Multimedia Subsystem.
For example, the S-CSCF, P-CSCF and I-CSCF may be SIP proxies
and the PoC server may be a SIP server, and the HSS may be a SIP registrar
in SIP networks. Alternatively, S-CSCF, P-CSCF, I-CSCF may be servers in
general networks, PoC server may be a server offering a service to users and
HSS may be a user database.
[0056] Furthermore, use of filter criteria, as described in the embodiment,
represent one mechanism to route certain requests to specific application
server(s). Any other mechanism or an address in the request may be used for
routing. The invention and its embodiments are thus not limited to the examples
described above but may vary within the scope of the claims.

CLAIMS
1. A method of routing a request in a communication system, comprising:
including in the request an identity that may be interpreted as an
identity of a first type or as an identity of a second type;
searching for routing information associated with the identity;
prioritizing one of routing information related to the identity of the
first type or routing information related to the identity of the second type; and
routing the request by using the prioritized routing information.
2. The method as claimed in claim 1, comprising prioritizing one of
the routing information in a network-wide operator definition.
3. The method as claimed in claim 1, comprising prioritizing one of
the routing information separately for one or more services.
4. The method as claimed in claim 1, comprising:
storing routing information related to at least one identity of the first
type and at least one identity of the second type in a database; and
prioritizing the routing information in the database.
5. The method as claimed in claim 4, comprising:
arranging the search for routing information so that the prioritized
routing information is always found before non-prioritized routing information.
6. The method as claimed in claim 4, comprising prioritizing the
routing information by a database function.
7. The method as claimed in claim 1, comprising:
querying routing information related to the identity; and
prioritizing the routing information in the querying network node.
8. The method as claimed in claim 1, comprising querying nonprioritized
routing information only if prioritized routing information is not available.
9. The method as claimed in claim 1, comprising:
querying routing information related to the identity of a first type and
to the identity of a second type; and
prioritizing by choosing one of the routing information related to the
identity of the first type or the routing information related to the identity of the
second type.
10. A network element, comprising:
storing means for storing routing information associated with an
identity;
searching means for searching for routing information based on an
identity that may be interpreted as an identity of a first type or as an identity of
a second type;
prioritization means for prioritizing, one of the routing information related
to the identity of the first type or the routing information related to the
identity of the second type; and
output means for outputting routing information, said output means
being arranged to output primarily prioritized routing information.
11. The network element as claimed in claim 10, wherein said prioritization
means are arranged to prioritize one of the routing information as a
network-wide operator definition.
12. The network element as claimed in claim 10, wherein said prioritization
means are arranged to prioritize one of the routing information separately
for one or more services.
13. The network element as claimed in claim 10, wherein the storing
means are arranged to store the routing information so that prioritized routing
information is always found before non-prioritized routing information.
14. The network element as claimed in claim 10, further comprising:
a database function arranged to choose prioritized routing information
over non-prioritized routing information.
15. A network element, comprising:
querying means for querying routing information for a request, said
querying means being arranged to include in the query an identity that may be
interpreted as an identity of a first type or as an identity of a second type;
prioritization means for prioritizing one of routing information related
to the identity of the first type orrouting information related to the identity of the
second type; and
information.
routing means for routing the request according to prioritized routing
16. The network element as claimed in claim 15, wherein said querying
means are arranged to query non-prioritized routing information only if
prioritized routing information is not available.
17. A computer program embodied in a computer readable medium,
the computer program implementing the steps of:
including in a request an identity that may be interpreted as an identity
of a first type or as an identity of a second type;
searching for routing information associated with the identity;
prioritizing one of routing information related to the identity of the
first type or routing information related to the identity of the second type; and
routing the request by using the prioritized routing information.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=Hb9iQH8UqvoTUFCCxQVYew==&loc=+mN2fYxnTC4l0fUd8W4CAA==

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Patent Number

269784

Indian Patent Application Number

1213/DELNP/2007

PG Journal Number

45/2015

Publication Date

06-Nov-2015

Grant Date

06-Nov-2015

Date of Filing

14-Feb-2007

Name of Patentee

NOKIA CORPORATION

Applicant Address

KEILALAHDENTIE 4, FI-02150, ESPOO,FINLAND

Inventors:

#	Inventor's Name	Inventor's Address
1	WESTMAN, IIKKA	KEURUUNTIE 3-13 E 21, FI-00510 HELSINKI, FINLAND

PCT International Classification Number

H04Q 7/22 , H04L 12/56

PCT International Application Number

PCT/FI2005/050290

PCT International Filing date

2005-08-15

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	20045298	2004-08-16	Finland