HK1095454B - Setting up communication sessions - Google Patents

Description

Establishing a communication session

Technical Field

The present invention relates to communication systems, and in particular to establishing communication sessions in a communication system in relation to time-critical services that are advantageous to a user's packet data communication session.

Background

A communication system can be seen as a facility that enables communication sessions to be conducted between two or more entities such as user equipment and/or other nodes associated with the communication system. The communication may include, for example, communication of voice, data, multimedia, and so on. A session may be, for example, a telephone call or a multi-way conference session between users, or a communication session between a user device and an Application Server (AS), for example, a service provider server. The establishment of these sessions generally enables various services to be provided to the user.

A communication system typically operates in accordance with a given standard or specification which sets out the various entities associated with the communication system and how that is permitted to operate. For example, the standard or specification may define whether the user, or more precisely the user equipment, has a circuit switched service and/or a packet switched service. Communication protocols and/or parameters to be used for the connection may also be defined, in other words a specific set of "rules" on which the communication may be based needs to be defined in order to be able to communicate with the system.

Communication systems providing wireless communication for user equipment are known. An example of a wireless system is a Public Land Mobile Network (PLMN). PLMNs are typically based on cellular technology. In cellular systems, a Base Transceiver Station (BTS) or similar access entity serves wireless User Equipment (UE), known as a Mobile Station (MS), over a radio interface between these entities. The communication over the radio interface between the user equipment and the communication network element can be based on a suitable communication protocol. The operation of the base station apparatus and other apparatus required for communication may be controlled by one or several control entities. The various control entities may be interconnected.

One or more gateway nodes may also be provided for connecting the cellular network to other networks, for example to a Public Switched Telephone Network (PSTN) and/or other communication networks such as an IP (internet protocol) and/or other packet switched data networks. In this arrangement, the mobile communications network provides an access network enabling a user with a wireless user equipment to access external networks, hosts, or services offered by a particular service provider. The access point or gateway node of the mobile communication network then provides further access to an external network or an external host. For example, if the requested service is provided by a service provider located in another network, the service request is routed to the service provider via the gateway. The routing may be based on definitions in mobile subscriber data stored by the mobile network operator.

An example of a service that may be provided to a communication system for a user, e.g. a subscriber, is a so-called multimedia service. Some communication systems capable of providing multimedia services are known as Internet Protocol (IP) multimedia networks. The IP Multimedia (IM) functionality may utilize an IP multimedia Core Network (CN) subsystem, or simply be provided by an IP Multimedia Subsystem (IMs). The IMS includes various network entities for providing multimedia services. Among other services, IMS services are intended to provide IP connectivity between mobile user equipment.

The third generation partnership project (3GPP) has defined General Packet Radio Service (GPRS) for providing IMS services, so it will be used below as an example of a possible backbone communication network capable of providing IMS services. An exemplary General Packet Radio Service (GPRS) operating environment includes one or more subnet service areas interconnected by a GPRS backbone network. The subnet includes a plurality of packet data Service Nodes (SNs). In this application, the serving node refers to a Serving GPRS Support Node (SGSN). Each SGSN is connected to at least one mobile communication network, typically to a base station system. The connection is typically made through a Radio Network Controller (RNC) or other access system controller such as a Base Station Controller (BSC), so that the mobile user equipment may be provided with packet services via several base stations. The intermediate mobile communications network provides packet-switched data transfer between the support node and the mobile user equipment. The different subnetworks are in turn connected to an external data network, e.g. a public switched data network (PSPDN), via a GPRS Gateway Support Node (GGSN). The GPRS service thus allows packet data transmission to be provided between the mobile data terminal and external data networks.

In such networks, packet data sessions are created to carry traffic flows over the network. Such a packet data session is often referred to as a Packet Data Protocol (PDP) context. The PDP context may include radio access bearers provided between the user equipment, the radio network controller and the SGSN, and switched packet data channels provided between the serving GPRS support node and the gateway GPRS support node.

The data communication session between the user equipment and the other party is then carried over the created PDP context. Each PDP context may carry more than one traffic flow, but all traffic flows within a particular PDP context are handled in the same way as they are transmitted on the network. The PDP context handling request is based on PDP context handling attributes, such as quality of service and/or charging attributes, associated with the traffic flow.

The third generation partnership project (3GPP) also defines a reference architecture for third generation (3G) core networks, providing users of user equipment with access to multimedia services. This core network is divided into three main domains. They are the Circuit Switched (CS) domain, the Packet Switched (PS) domain and the internet protocol multimedia (IM) domain. The latter of these domains, the IM domain, is used to ensure adequate management of multimedia services.

The IM domain supports the Session Initiation Protocol (SIP) developed by the Internet Engineering Task Force (IETF). Session Initiation Protocol (SIP) is an application-layer control protocol for creating, modifying and terminating sessions with one or more participants (endpoints). SIP was generally developed to allow for the initiation of sessions between two or more internets by making endpoints in the two or more internets aware of session semantics. A user connected to a SIP-based communication system may communicate with various entities of the communication system based on standardized SIP messages. A user device or a user running some application on the user device registers with the SIP backbone so that an invitation to a particular session can be properly delivered to these endpoints. To achieve this, SIP provides a registration mechanism for devices and users, and applies mechanisms such as location servers and registrars to route session invitations appropriately. Examples of possible sessions that may be provided using SIP signaling include internet multimedia conferences, internet telephone calls and multimedia distribution.

It is desirable to be able to provide various types of services over IMS systems using different Application Servers (AS). Some services may be time critical. An example of a time-critical service that can be provided over IMS is the so-called direct voice communication service. A more specific example is the "Push-to-talk over Cellular (PoC) service, also known as PTT or Push-to-talk service. Direct voice communication services are intended to use the functionality of the IP Multimedia Subsystem (IMS) for IP connectivity of mobile user equipment and other communication parties, such as other network related mobile user equipment or entities. The service allows a user to engage in intermediate communications with one or more other users.

In the PoC service, communication between a user equipment and a PoC application server is performed over a one-way communication medium. The user may open the communication medium by simply pressing a tangential key, such as a button on the keyboard of the user device. The push-to-talk button may be a specific button or any suitable key of a keypad. While one user speaks, the other user or users may hear. Two-way communication may be provided because all parties to the communication session may communicate voice data with the PoC application server as well. The order of speaking is requested by pressing the push-to-talk button. The speaking order may be authorized, such as by speaking first or by priority. Hence the name "push-to-talk". The user may join the group session with which they want to speak and then press the tangent key to begin speaking.

In a conventional session setup procedure, the media capabilities of the user equipment are agreed upon during the session setup procedure. For example, PoC communication between two user equipments (one-to-one communication) or addition to a PoC group in one-to-many communication requires a SIP session on the control panel. This time alone is quite long, especially when considering the need for time-critical services. On the other hand, the push-to-talk type instant services are real-time services according to their characteristics. Thus, the user panel connection should be free of unnecessary delay after giving a specific tangential or additional indication to the user device whose user wants to speak to the other party. However, due to the nature of the setup procedure required for a PDP context, it may take a certain time until the appropriate data connection is provided from the request of owning a connection. For example, in IMS networks compliant with 3GPP release5, PDP context activation and radio access bearer establishment time typically take more than 3 seconds.

Thus, there may not be time for a proper end-to-end media performance agreement, as the media performance agreement may take too long in the beginning of the session. This may have various disadvantageous drawbacks. For example, one problem is how to provide sufficient codec settings from the beginning of a session. If not enough codec information is available, the burst may use an unnecessarily low codec for the type of communication desired. Other examples of possible performance information that may need to be agreed upon are given in the detailed description.

Thus, it may be advantageous if performance negotiation may be done appropriately for establishing a session. However, if even more time is needed for establishing a session, it is possible that users may become frustrated and no longer wait long enough to be able to provide their requested services to them. Too long a latency may also be considered insufficient from a service level point of view. If the caller has to wait too long for the start-to-talk-indication (start-to-talk-indication), he/she may assume that the request was not successful. The caller may then even re-press the tangent key. Pressing the tangent key again results in a new SIP session establishment procedure, consuming network resources and further delaying the establishment of the session.

Disclosure of Invention

According to one embodiment of the present invention, a method for establishing a data session is provided. The method comprises the following steps: at least one user device is registered with a service provider and then information about media capabilities is transferred between the at least one user device and the service provider and stored. The method also includes sending a request to establish a data session with the at least one user device, and using the stored information when establishing the requested data session.

According to another embodiment of the present invention, a communication system for providing services to its users is provided. The communication system includes: a communication network for providing at least one user equipment capable of accessing at least one data network; a data network connected to the communication network; and an application server connected to the data network. The application server is for communicating information about media capabilities with at least one user equipment before a data session with the at least one user equipment is requested, storing the information about the media capabilities in a memory, and using the information from the memory when establishing the requested data session.

According to another embodiment of the invention, an application server for providing a service to a user equipment connected to a communication network is provided. The application server is connected to a data network. The application server is for communicating information about media capabilities with the at least one user equipment before a data session with the at least one user equipment is requested, storing the information about the media capabilities in a memory, and using the information from the memory when establishing the requested data session.

According to another embodiment of the invention, there is provided a user equipment configured to connect to a communication network. The user equipment is configured to communicate information about media capabilities with an application server connected to a data network via a communication network and the data network before a data session request with said user equipment is sent to the application server.

Embodiments of the present invention have various advantages. In some applications, the time required to establish a voice connection or other connection with appropriate media capabilities may be reduced. In some embodiments, the latency of sessions required to provide time-critical services may be shorter. Unnecessary repetition of session requests can also be avoided. This may save resources of the network and the user equipment. These embodiments may improve the availability of services, in particular time critical services.

Drawings

For a better understanding of the present invention, reference is now made, by way of example, to the accompanying drawings in which:

FIG. 1 illustrates a communication system in which the present invention is embodied;

FIG. 2 illustrates a flow chart of operation of an embodiment of the present invention;

FIG. 3 illustrates a possible media performance negotiation process;

fig. 4 shows a possible session establishment procedure for a calling user equipment; and

figure 5 shows a possible session set-up of the called user equipment.

Detailed Description

Certain embodiments of the present invention will be described by way of example with reference to the exemplary architecture of a third generation (3G) mobile communication system. However, it should be understood that the embodiments may be applied to any other suitable network form. A mobile communication system is typically arranged to serve a plurality of mobile user equipment, typically via a wireless interface between the user equipment and a base station of the communication system. The mobile communication system may be logically divided between a Radio Access Network (RAN) and a Core Network (CN).

Referring now to fig. 1, fig. 1 illustrates an example of a network architecture in which the present invention may be embodied. Fig. 1 shows an IP multimedia network 45 for providing IP multimedia services to IP multimedia network subscribers. IP Multimedia (IM) functionality may be provided using a Core Network (CN) subsystem that includes various entities for providing services.

The base stations 31 and 43 are arranged to transmit signals to and receive signals from mobile user equipment 30 and 44 of mobile users, i.e. subscribers, over a wireless interface. Thus, each mobile user equipment is able to transmit signals to and receive signals from the base station over the wireless interface. In the simplified representation of fig. 1, the base stations 31 and 43 belong to respective Radio Access Networks (RANs). In the arrangement shown, each user equipment 30 and 44 may access the IMS network 45 via two access networks associated with the base stations 31 and 43. It should be understood that a typical mobile communication network typically comprises a plurality of radio access networks, although for simplicity fig. 1 shows only base stations of two radio access networks.

The 3G Radio Access Network (RAN) is typically controlled by a suitable Radio Network Controller (RNC). This controller is not shown for the sake of simplicity. One controller may be assigned to each base station, or one controller may control a plurality of base stations. Solutions are also known in which controllers are provided both in the individual base stations and at the radio access network level for controlling a plurality of base stations. Thus, it should be understood that the name, location, and number of network controllers are system dependent.

The mobile user may use any suitable mobile device suitable for Internet Protocol (IP) communication in order to connect to the network. For example, a mobile user may access a cellular network through a Personal Computer (PC), a Personal Digital Assistant (PDA), a Mobile Station (MS), and so on. The following examples are described in the context of a mobile station.

One skilled in the art is familiar with the features and operation of a typical mobile station. Therefore, a detailed explanation of these features is not necessary. It suffices to note that the user may use the mobile station for tasks such as making and receiving phone calls, receiving and sending data from and to the network, and experiencing e.g. multimedia content. Mobile stations typically have a processor and memory device to accomplish these tasks. The mobile station may comprise antenna means for wirelessly receiving signals from or transmitting signals to base stations of the mobile communication network. The mobile station may also have a display for displaying images and other graphical information of the user of the mobile user equipment. Speaker means may also be provided. The operation of the mobile station may be controlled by means of a suitable user interface, such as control buttons, voice commands and the like.

The mobile stations 30 and 44 are capable of using push-to-talk type services. The tangential functionality that may be required for push-to-talk services may be provided by a button on the usual keypad of the mobile stations 30 and 44 or a specific tangential key, the latter with a tangential direction known from "walkie-talkie" devices, for example. Voice activation may also be used. In this case, the detected sounds may be used to trigger the establishment of a session for transmitting voice or other data. Instead of a key operation, the user may also activate the service by selecting an appropriate menu. The manner in which the mobile station activates the service is an implementation issue and will not be described in detail.

Although only two mobile stations are shown in fig. 1 for simplicity, it should be understood that multiple mobile stations may be in simultaneous communication with each base station of the mobile communication system. The mobile station may also have several simultaneous sessions, e.g. multiple SIP sessions and activated PDP contexts. The user may also have a telephone call and be connected to at least one other service at the same time.

The Core Network (CN) entities typically include various control entities and gateways for communicating over multiple radio access networks and for interfacing a single communication system with one or more communication systems, such as other cellular systems and/or fixed line communication systems. In fig. 1, GPRS service support nodes 33, 42 and GPRS gateway support nodes 34, 40 are used to provide support for GPRS services 32, 41, respectively, in the network.

The radio access network controller is typically connected to one or more appropriate core network entities such as, but not limited to, serving general packet radio service support nodes (SGSNs) 33 and 42. Although not shown, each SGSN is typically capable of accessing a designated subscriber database for storing information related to subscriptions of the corresponding user equipment.

User equipment in a radio access network may communicate with a radio network controller via radio network channels, commonly referred to as Radio Bearers (RBs). Each user equipment may have one or more radio network channels that are open at any one time simultaneously with the radio network controller. The radio access network controller communicates with the PRS serving support node via an appropriate interface, e.g., the Iu interface.

The GPRS serving support node then typically communicates with a GPRS gateway support node via GPRS backbone networks 32 and 41. This interface is typically a switched packet data interface. The GPRS service support node and/or the GPRS gateway support node are used to provide support for GPRS services in the network.

The entire communication between the user equipment in the access entity and the GPRS gateway support node is typically provided by a Packet Data Protocol (PDP) context. Each PDP context typically provides a communication path between a particular user equipment and the GPRS gateway support node and, once established, may typically carry multiple flows. Each flow generally represents, for example, a particular service and/or a media component of a particular service. Thus, a PDP context often represents a logical communication path for one or more flows on a network. In order to implement a PDP context between the user equipment and the GPRS serving support node, a Radio Access Bearer (RAB) is established which generally allows the user equipment to perform data transfer. The implementation of these logical and physical channels is known to those skilled in the art and will not be discussed further.

The user equipment 30 and 44 may be connected via a GPRS network to application servers that are typically connected to the IMS. In fig. 1, this application server is provided by a push-to-talk over cellular (PoC) service server 50. The server 50 is used to provide push-to-talk over cellular (PoC) services over the IMS network 45. The push-to-talk service is an example of a so-called direct voice communication service. A user who wishes to use the PoC service may need to subscribe to an appropriate PoC server. Registration with the IMS to the PoC service may then be performed by the IMS using an appropriate third party registration procedure. Preferably, the PoC server has suitable memory means for storing information relating to the capabilities of the registered user equipment. Thus, fig. 1 shows the memory means 52 of the PoC application server 50.

The direct voice communication service is intended to use the capabilities of the GPRS backbone and the control functions of the multimedia subsystem (IMS) to enable IP connectivity for the mobile stations 30 and 44. The PoC application server may be operated by the operator of the IMS system or a third party service provider. A more detailed explanation of how the service allows the user of the mobile station 30 (party a) to engage in an intermediate communication with the user of the mobile station 44 (party B) will be given later in this description.

The user may open a communication session, for example, by simply pressing a particular button on mobile station 30. When the user of the mobile station 30 speaks, the user of the mobile station 44 listens. The user of the mobile station 44 may then respond in a similar manner.

The communication system may already provide services for the user equipment with various functions of the network, which are handled by network entities known as servers. For example, in existing third generation (3G) wireless multimedia network architectures, it is assumed that several different servers are used to handle different functions. These functions include, for example, Call Session Control Functions (CSCFs). The call session control function may be divided into various categories such as a proxy call session control function (P-CSCF), an interrogating call session control function (I-CSCF), and a serving call session control function (S-CSCF). A user wishing to use a service provided by an application server via an IMS system may need to register with a service control entity. The serving call session control function (S-CSCF) may form an entity in the 3G IMS arrangement for which the user needs to register to be able to request services from the communication system.

It should be understood that similar functionality may be referred to by different names in different systems. For example, in some applications, a CSCF may be referred to as a call state control function.

The communication system may be arranged such that a user who has been provided with the required communication resources by the backbone network has to initiate the use of the service by sending a request for the desired service in the communication system. For example, a user may request a session, transaction, or other type of communication from an appropriate network entity.

Signalling between the user equipment and the appropriate call state control functions is routed via the GPRS network. The user plane session establishment signalling of the user equipment is routed via the PoC application server 50 and controlled by the PoC application server 50, i.e. both the control plane and the user plane of the PoC user are controlled by PoC. It will be appreciated that control panel traffic between the PoC application server and the user equipment is routed via the IMS45, while user panel traffic between the user equipment and the PoC application server is routed from the GPRS system to the PoC application server over the interfaces 54 and 56.

Embodiments are based on the recognition that it would be advantageous if at least a part of the medium performance agreement could be performed for time-critical services before the actual communication of data is activated. Media performance negotiation may be required for the communication of various performance information between a particular user device and an application server. Non-limiting examples of user equipment specific information that may need to be provided for the application server include port information, i.e. the port at which the application server sends the medium, information about the type and version of the user equipment, timing information, information about supported codecs and modes, information about supported optional features, etc. The user equipment may also provide information to the application server about the capabilities of the wireless interface it has with the wireless network. For example, information about the capacity and quality of the radio interface, and any quality of service restrictions, etc. may be communicated to the application server. It may be desirable to provide the user equipment with application server specific information, e.g. information about the server version, optional features supported, possible timers, services available to the subscriber, pre-paid or post-paid accounts, etc.

In the following an embodiment will be described wherein the capabilities of the user equipment are notified to the application server before using the service provided by the application server. In this embodiment, following initial registration with the IMS system, the user equipment performs a media performance negotiation with the time critical application server or servers.

Reference is now made to fig. 2. In step 100, the user equipment registers on the desired service provider application server. According to one embodiment, the mobile station 44 first registers with the IMS, e.g., with the serving CSCF 38. Third party registration of the mobile station 44 may then occur with the PoC applicator 50 after the mobile station 44 successfully registers over the IMS. This may be done automatically for each user who has subscribed to the PoC service. In this way, the user may not need to take any action at this stage. The third party registration may be provided by a third party registration procedure between the IMS and the PoC application server.

The user equipment may then perform a media negotiation with the application server in step 102, following a third party registration by the S-CSCF. This agreement may be performed, for example, using SIP INVITE, SIP MESSAGE or SIP OPTIONs messages communicated between the user device and the application server, as shown in fig. 3. When the performance information is received by the application server, the application server stores it in its database in step 104. In step 108, in response to the a-party user device requesting in step 106 to establish a communication session with the user device registered in steps 100 to 104, the application server 50 may use the stored media capability information for establishing the requested session. Thus, further media performance negotiations may be avoided at this stage.

The media capabilities associated with the a-party user equipment may be included in the session request. Alternatively, the application server may use information stored in its database that is also used for the a-party user equipment.

Referring now to fig. 3, fig. 3 illustrates a possible mechanism for media performance negotiation. PoC enables the user equipment 44 to send an appropriate SIP message1 immediately after PoC registration. SIP MESSAGE1 may carry performance information required by the user equipment.

The PoC server 50 receives SIM MESSAGE3 the capability information and stores the information in its database 52. In this way, the user plane parameters of the B-party user equipment 44, e.g. the port number, required for communication between the PoC application server and the B-party user equipment are made available to the PoC application server. Many users may similarly register with the PoC application server. Other user equipments may perform similar performance negotiations and thus parameters for a plurality of user equipments may be stored in the PoC application server. The PoC application server may send a SIP200OK message 4 back to the user equipment 44 when all necessary information is available. Upon receipt of the SIP200OK message 6, the user equipment knows that the capability information has been registered and can start using the service whenever required.

Figure 4 shows possible signalling between the user equipment 30 and the PoC application server 50 after the B-party user equipment 44 registers its media capabilities with the application server. Figure 5 shows the communication between the PoC application server 50 and the B-party user equipment 44. The circled characters a and B in fig. 4 and 5, respectively, indicate where the signaling flow diagrams of fig. 4 and 5 may be mapped to each other, thereby obtaining a more complete signaling description for the connection activation procedure between the a-party user equipment 30 and the B-party user equipment 44.

In step 10 the user gives an indication that he/she wishes to establish a voice connection with party B. The user equipment 30 may then send SIP INVITE a message 11 to the IMS45 to be routed to the PoC application server 50 for requesting a voice connection with the B-party. The IMS may send a SIP100TRYING message 12 back to the user equipment 30 to determine that it has received the request.

The IMS45 forwards SIP INVITE to the PoC application server 50 as message 13. Upon receiving this message, the application server may send a SIP100TRYING message back to the IMS to determine that it has received the request.

Once the application server receives a determination from the IMS that a request has been received (see message 21 in fig. 5), the application server may send a SIP200OK message 15 to the IMS. This message may even be sent before the B-party user equipment 44 has received the request or any indication that such a request may be desired. The SIP200OK is then forwarded to the user equipment 30 in message 16. In response to the reception 16, the user device 30 may then give an indication to the user of the user device that he/she can start speaking in step 17. The user equipment 30 may also indicate that the OK message has been received by sending a SIP ACK message 18 to the IMS. The message may then be forwarded to the PoC application server 50 as message 19.

As shown in fig. 5, in response to receipt of SIP INVITE message 13 in fig. 4, the PoC application server 50 may send SIP INVITE message 20 to the IMS to be routed to the B-party user equipment 44. The IMS may send a SIP100TRYING message 21 back to the application server to determine that it has received the message. The IMS45 forwards SIP INVITE as message 22 to the PoC enabled B-party user equipment 44. Upon receipt of this message, the B-party user equipment 44 may send a SIP100TRYING message 23 back to the IMS to determine that it has received the request.

SIP once the required processing is completed on the B-party device 44 and the request can be satisfied

A 200OK message 24 is sent to the IMS. The B-party user equipment 44 may also give its user an indication to start listening in step 25. An indication of an incoming PoC "talk" session may be provided to the B-party user immediately prior to the outgoing talk burst from the a-party.

The SIP200OK is forwarded from the IMS to the PoC application server 50 in message 26. PoC application server 50 may determine that OK message 26 is received by sending a SIP ACK message 27 to the IMS. This message may then be forwarded as message 28 to the B-party user equipment 44.

An early agreement on the user equipment media capabilities may speed up the session establishment. The message provided to the application server may be particularly useful if the user plane connection between the two user devices 30 and 44 requires any changes due to, for example, different communication link characteristics. If the application server (or application servers) knows the media parameters in advance, it may agree with the user equipments on these parameters before communication between the user equipments, e.g. before the first talk burst is transmitted from one user equipment to another in a PoC application. Performance negotiation, such as codec performance, does not take time in establishing an actual communication session. A properly set codec can be used to guarantee the quality of the voice connection. The application server may store performance information for all user devices registered with the application server.

In a further embodiment, the user device may be provided with an application server "always on session". This process may be referred to as the establishment of a "pre-session", "early session", or "always on session", for example. In this case, the media performance negotiation is preferably performed during the setup period of the "always on session" setup. After registering with the application server in step 100 of fig. 2, the user equipment may automatically request the establishment of an "automatically opened session". To facilitate fast establishment of the session, the PDP context of the user may be activated and the required Radio Access Bearer (RAB) may also be automatically established in response to registration with the application server. The pre-establishment of the PDP context may be performed using a SIP session for activating the PDP context before sending the request for the communication session, or using another suitable PDP context activation procedure. The establishment of Radio Access Bearers (RABs) may be accomplished by a suitable RAB assignment procedure. In order to provide sufficient instant services to the user, it is preferred to provide an "always on" session between the user device and the application before the actual request for any voice or other session is made. The already established communication session may then be used for communication between the user equipment and the application server.

The pre-established "always-on" session provides substantially instant communication between the end user and his/her home PoC application server. The communication may be communicated from the user equipment to the PoC application server in response to the user of the user equipment pressing a tangent key of the user equipment, wherein pressing of the toggle key opens a voice connection to the PoC server. Because the PDP context has been established, the communication request may be communicated to the PoC application server using any suitable signaling protocol. It will be appreciated that this is an application level issue and may be provided in various ways. For this purpose, communication network standards, such as 3GPP, are not typically strictly defined in a particular protocol. To give an example, the real-time transport protocol (RTP) or RTP control protocol (RTCP) may be used for the sending of the request. These protocols may be used together or separately. The request may also be sent using SIP. The packets may be transmitted based on, for example, User Datagram Protocol (UDP) or Transmission Control Protocol (TCP).

The "always on" session enables the mobile station to know to which IP address and port of the PoC application server the RTP/RTCP packets should be directed. The RCP/RTCP payload includes sufficient addressing information for routing RTP/RTCP packets to the B-party mobile station 44.

When a voice connection request is finally made, it may be necessary for the PoC server for the B-party to be identified. The user may select the B-party user or target group from a menu on the mobile station and then press the "push-to-talk" key on the mobile station. The required identity information may be added by the mobile station to the signaling transmitted to the PoC application server over the "always on" session.

According to another embodiment, information relating to the capabilities of the application server is provided for the user equipment and stored therein for further use. It is also possible that the user equipment and the application server exchange required performance information with each other in step 102 of fig. 2 before making a request for a communication session.

According to one embodiment, the user equipment sends information about the capabilities that can be used. The application server receives the performance information and treats the information as a recommendation. After having analyzed the performance, the application server may then send back information about the performance to be used for the next session. The analysis and decision making herein may be based on a variety of information. For example, if a group session is to be established, the application server may analyze the capabilities of all user equipments comprised in the session and set the capabilities such that all members of the group can participate in the session.

The above describes a solution for time critical services like PoC based on a general application server. However, it should be understood that the present invention may be used with other services without departing from the spirit and scope of the present invention.

This concept provides an opportunity for end manufacturers to implement push-to-talk facilities for various classes of user equipment, thereby providing end users with more freedom to select products that best meet their communication needs.

It should be appreciated that whilst embodiments of the present invention have been described in relation to user equipment such as mobile stations, embodiments of the present invention may be used with any other suitable type of user equipment.

Examples of the invention have been described in the context of an IMS system and a GPRS network. The invention can also be used for any other access technology. Additionally, the examples given are described in the context of a SIP network having SIP-enabled entities. The invention may also be used with any other suitable communication system, wireless system or fixed line system, standard and protocol.

It should be understood that although only one PoC application server is described in figure 1 and the preceding description, many such servers may be provided. The a-party and B-party user equipment may register with different PoC application servers. The application servers serving the a-party and the B-party may even be located in different networks.

Embodiments of the present invention have been discussed in the context of a call state control function. Embodiments of the present invention may be used with other available network elements.

It is also noted that while the above describes exemplifying embodiments of the invention, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention as defined in the appended claims.

Claims (35)

1. A method for establishing a data session, the method comprising:

registering at least one user device at a service provider;

receiving, at the service provider, information about media capabilities from the at least one user device;

storing information about the media capabilities;

receiving a request for a data session with the at least one user device; and

using the stored information when establishing the requested data session, wherein the information on media capabilities comprises information related to available communication ports and codec capabilities, and wherein receiving the information on media capabilities comprises: receiving at least one session initiation protocol invite (SIP invite) message from the at least one user equipment.

2. The method of claim 1, wherein receiving information about media capabilities comprises: receiving information regarding media capabilities of the at least one user equipment, and storing the information comprises: storing the media capability information of the at least one user equipment at the service provider.

3. The method of claim 2, wherein the information about the performance of the medium comprises information relating to at least one of the following features: mode performance; type and/or version of user equipment; a timer; supported selectable features; the performance of the radio bearer provided for the user equipment.

4. The method of claim 1, further comprising: information about the media capabilities is sent from the service provider to the at least one user equipment.

5. The method of claim 4, wherein the information about media capabilities sent from the service provider to the at least one user equipment comprises information relating to at least one of the following features: a version of the application server; supported selectable features; a timer; available services; an account.

6. The method of claim 1, wherein registering a user device comprises: registering the user equipment with a push-to-talk application server.

7. The method of claim 1, further comprising registering the user equipment with an internet protocol multimedia subsystem and subsequently automatically registering the user equipment with the service provider.

8. The method of claim 1, wherein receiving information about media capabilities comprises: the information is received automatically after registration of the user device at the service provider.

9. The method of claim 1, wherein the registering a user device at a service provider comprises: third party registration of the user equipment by the internet protocol multimedia subsystem.

10. A method according to claim 1, comprising communicating over a packet switched communications network.

11. The method of claim 10, wherein the data session comprises a packet data protocol context.

12. The method of claim 1, comprising opening an instant user panel communication session between the user device and the service provider in response to receiving a session request from another user device.

13. A method according to any preceding claim, further comprising receiving, at the service provider, information from the user device relating to media capabilities that the user device can provide for a communication session to be established later, analysing, at the service provider, the information relating to available media capabilities, and sending information from the service provider to the user device relating to the media capabilities for use by the user device for a subsequent communication session.

14. A method for establishing a data session, comprising:

sending a registration request from at least one user device to a service provider;

receiving, at the at least one user equipment, information from the service provider regarding media capabilities;

storing information about the media capabilities;

receiving, at the at least one user equipment, a request for a data session; and

when the requested data session is established, the stored information is used,

further comprising sending information on media capabilities from said at least one user equipment to said service provider, wherein the information on media capabilities sent from said at least one user equipment to said service provider comprises information on available communication ports and codec capabilities,

and wherein transmitting information about the media capabilities comprises: sending at least one session initiation protocol invite (sip invite) message from the at least one user equipment.

15. The method of claim 14, wherein the information about media capabilities sent from the at least one user equipment to the service provider comprises information relating to at least one of the following features: mode performance; type and/or version of user equipment; a timer; supported selectable features; capability of a radio bearer provided for at least one user equipment.

16. The method of claim 14, wherein receiving information about media capabilities comprises: receiving information about media capabilities of the service provider, and storing the information comprises: storing the media capabilities of the service provider at the at least one user device.

17. The method of claim 16, wherein the information about media capabilities sent from the service provider to the at least one user equipment comprises information relating to at least one of the following features: a version of the application server; supported selectable features; a timer; available services; an account.

18. The method of claim 14, wherein sending a registration request comprises: a registration request is sent to a push-to-talk service application server.

19. The method of claim 14, further comprising: sending a registration request to an internet protocol multimedia subsystem, and subsequently automatically registering the user equipment with the service provider.

20. The method of claim 14, wherein receiving information about media capabilities comprises: the information is automatically received after registering the at least one user device with the service provider.

21. The method of claim 14, wherein sending the registration request comprises a third party registration of the at least one user equipment by an internet protocol multimedia subsystem.

22. A method according to claim 14, comprising communicating over a packet switched communications network.

23. The method of claim 22, wherein the data session comprises a packet data protocol context.

24. The method of claim 14, comprising: an instant user panel communication session is opened between at least one user device and a service provider in response to receiving a session request from another user device.

25. The method of claim 14, comprising: storing information about media capabilities of at least two user equipments in said service provider before said service provider sends a data session request.

26. The method of claim 25, comprising establishing a multi-user session using the stored information.

27. A method according to any of claims 14-26, further comprising sending from the user equipment information relating to media capabilities that the user equipment can provide for a communication session to be established later, and receiving from the service provider information about the media capabilities for use by the user equipment for a subsequent communication session.

28. A communication system for providing services to users thereof, the communication system comprising:

a communication network for providing at least one user equipment with access to at least one data network;

a data network connected to the communication network; and

an application server connected to the data network for communicating information about media capabilities with at least one user device before a data session with the at least one user device is requested, storing the information about media capabilities in a memory, and using the information from the memory when establishing the requested data session;

wherein the information on media capabilities sent from the at least one user equipment to the application server comprises information related to available communication ports and codec capabilities, and wherein the receiving the information on media capabilities from the at least one user equipment comprises: receiving at least one session initiation protocol invite (SIP invite) message from the at least one user equipment.

29. An application server for providing a service to user equipment connected to a communications network, said application server being connected to a data network and configured to communicate information about media capabilities with at least one user equipment before requesting a data session with the at least one user equipment, to store the information about media capabilities in a memory, and to use the information from said memory when establishing the requested data session;

wherein the information on media capabilities sent from the at least one user equipment to the application server comprises information related to available communication ports and codec capabilities, and wherein the receiving the information on media capabilities from the at least one user equipment comprises: receiving at least one session initiation protocol invite (SIP invite) message from the at least one user equipment.

30. An application server as in claim 29, comprising a push-to-talk service application server.

31. An application server as claimed in claim 29 or 30, configured to connect to an internet protocol multimedia subsystem.

32. An application server according to claim 29 or 30, arranged to store information about the media capabilities of all user equipment registered with the application server.

33. A user equipment configured to be connected to a communications network, the user equipment being configured to communicate information about media capabilities with an application server connected to the data network via the communications network and the data network before a data session request with the user equipment is sent to the application server, to store the information about the media capabilities of the application server in a memory, and to use the information from the memory when establishing the requested data session;

wherein the information on media capabilities sent from at least one user equipment to the application server comprises information related to available communication ports and codec capabilities, and wherein the receiving the information on media capabilities from the at least one user equipment comprises: receiving at least one session initiation protocol invite (SIP invite) message from the at least one user equipment.

34. The user equipment of claim 33, wherein the user equipment is configured to transmit information about media capabilities of the user equipment to an application server.

35. A user equipment according to claim 33 or 34, wherein the user equipment is configured to receive information about media capabilities of an application server and to store information about media capabilities of the application server.