GB2439407A

GB2439407A - Supplementary call services provided via a IP Multimedia Network

Info

Publication number: GB2439407A
Application number: GB0705413A
Authority: GB
Inventors: Craig Kelvin Bishop; Chen Ho Chin; Osok Song
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2006-06-19
Filing date: 2007-03-21
Publication date: 2007-12-27
Anticipated expiration: 2027-03-21
Also published as: GB0612129D0; GB0705413D0; GB2439407B; GB2439365A

Abstract

The control of supplementary services to a mobile terminal in a communications network (including a circuit switched cellular network and an IP Multimedia Network) is carried out in the IP Multimedia Network independent of whether a call is carried out via the circuit switched network or the IP Multimedia Network. The mobile terminal transmits information relating to the terminal's capabilities to support centrally controlled supplementary services to the network. Also, a network element transmits information relating to the network element's capabilities or intention to support centrally controlled supplementary services to the terminal. If a user handset is unable to receive supplementary services via the IP Network, then these are provided via the circuit switched network. This simplifies the provision of supplementary services, and also provides improved call continuity, particularly for dual handset users.

Description

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Mobile Communications This invention relates providing call related services in a communications system including a cellular communications network and a IF network, such as an IP Multimedia Subsystem (I1MS). More explicitly, but not exclusively, the invention relates to providing call related services by the IMS when the user is connected via the circuit switched (CS) domain.

The IP Multimedia subsystem provides a generic architecture for offering Voice over [P (VoIP) and multimedia services. In an IMS service is provided using the Signalling Protocol for Internet Telephony (SiP). The SIP is used to thus enable service providers to integrate basic IP telephony and other services over the IF network,. SIP allows establishing sessions for features such as audio-and videoconferencing, interactive gaming, and call forwarding to be deployed over IF networks.

A cellular communications system includes mobile user equipment (UEs), a radio access network (RAN) and one or more core networks (CNs), as illustrated in Figure 1 for the UMTS case. A detailed overview over the architecture of a cellular telecommunications system of the third generation may be found in the 3GPP specification "UTRAN Overall Description" 3GPP TS25.401 and related specifications. Communication between the UEs and the UTRAN is provided via the Uu interface (Uu), whereas the communication between the UTRAN and the core networks is done via the lu interface (lu). This invention applies equally to other Radio and Fixed Access Networks (e.g. GERAN, TISPAN, etc) connected to an IMS Core Network.

Referring now to Figure 2, the architecture of a circuit switched domain is illustrated. The RAN comprises base stations, such as the so-called Node B's for the UTRAN, and radio network controllers (RNC) , also referred to as base station controllers (BSC). The base stations handle the actual communication across the radio interface, covering a specific geographical area also referred to as a cell. The RNCs control the base stations connected to it, and also include other functionality for tasks such as the allocation of radio resources, i.e. the local mobility. An RNC is connected to one or more core networks via the lu interface, to a number of base stations via the Jub interface and possibly to one or more other RNCs via the lur interface.

In a UMTS network, the Radio Resource Control (RRC) protocol is used to across the radio interface, i.e. between the UE and UTRAN. These protocol end points interact by exchanging protocol parameters, by sending messages comprising of one or more information elements.

As can be seen from Figure 2, the core network includes a serving GPRS (General Packet Radio Service) support node (SGSN), Circuit Switched Media Gateway Functions (CS-MGW), a Gateway MSC Server (GMSC), a Gateway GPRS Support Node (GGSN), and a Home Subscriber Server (HSS) including Home Location Register (HLR) and an Authentication Centre (AuC).

The CN also includes the IF Multimedia Subsystem (IMS). Fig. 3 illustrates the architecture of an IMS. The IMS related elements include a Call Session Control Function (CSCF), a Media Gateway Control Function (MGCF), a MS Media Gateway function (MS-MGW), a Multimedia Resource Function Controller (MRFC), a Multimediate Resource Function Processsor (MRFP), a Breakout Gateway Control Function (BGCF), and a Home Subscriber Server (HSS). The UE is connected to the IMS via a Proxy CSCF (P-CSCF). The MRFP and the BGCF are connected to a IP Multimedia Network, whereas the IMS-MGF and MGCF are connected to a Public Switched Telephone Network (PSTN). More details may be found in the

3GPP Specification TS 23.002 "Network Archicture".

In a network including both a CS domain and an IMS, a mobile terminal can connect to the network either via the CS domain or the IMS.

Both networks provide call related services, also known as supplementary services. Supplementary Services for example include call forwarding, call redirecting, call holding, and call re-routing.

Presently Supplementary Services are controlled in the domain via which the UIE connects to the network. Thus for a CS based call the associated Supplementary Services are provided by entities of the CS network. Call related services are now being defined (see for example the specification TS 183 007 by ETSI for more details) for calls placed via the IP Multimedia Subsystem (IMS). Those services at present for the most part emulate the Supplementary Services of the CS domain, with control resting in the IMS. It is expected that additional new services will also be developed in the IMS for Multimedia Telephony, and that some operators may wish also to provide such services in the IMS for CS voice calls, rather than having to also emulate those services in the CS domain.

The advent of dual mode terminals where the user can place and receive calls via the CS domain or via the IMS has resulted in a situation where the control of call related services for such terminals is distributed between domains depending on via which domain the UE is connected. This is known as distributed control. One problem of this approach is that the users of dual mode terminals may receive inconsistent provision of services between domains. For example, services may be presented differently to the user when connected to the CS domain than they are to the user when connected to the IMS. Even more problematic is the transition from the CS domain to the IMS (and vice-versa) during a call. Such a transition is known as Voice Call Continuity (VCC). In that case, mid-call services like, for example, multiparty calling, call waiting, or the like, cannot be guaranteed to work when the user's call is transferred from the CS domain to the IMS. To allow progress in standardisation work, in release 7 of the VCC specifications, domain transfer is likely to be prohibited during the execution of mid-call services.

It is generally accepted that in the long run centralised control of call related services throughout the network is envisaged. Centralised control means that the call related services are controlled by one of the networks, independent of the network serving the mobile terminal. It is understood that supplementary services are to be controlled by the IMS network rather than the Circuit Switched domain (see for example the 3GPP working report TR

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23.806, available from http://www.3gpp.org/fip). However, it appears that completely centralised control of call related services cannot be achieved immediately, or in a single step. Therefore, a phased roll out of networks and UE supporting centrally controlled services may be required. For this reason, and even when the final goal of centrally controlled service availability is achieved, there will be a mixture of UB and networks supporting either centrally controlled services, services with distributed control, or both.

Further, there may be circumstances in which the network operator would prefer not to offer IMS services to a CS connected subscriber due to the user roaming to a visited network, or because of a problem in the home IMS.

For example, in order to receive IMS centralised services, all CS originated calls from the UE will be routed to the user's home network, where a SIP AS or some other IMS adaptor will act as the UE's proxy making it appear that the UE has connected via the PS domain using [MS. In the case where the UE is roaming, this will involve an international call leg being established for transport of the media between the roaming UE and the user's home network. This has a not insignificant associated cost, and if the UE is calling a local number (in the same VPLMN) the "tromboning" of the media traffic from the visited network to the home network and back to the visited network is particularly redundant (i.e. incurring two unnecessary international call legs). As such, the network may wish to indicate to the UE that in the case where it is roaming it should a) not expect to receive IMS Centralised Services (and therefore not route the CS call via the home network) unless the call is to a UE in the home network, and/or b) not expect to receive [MS Centralised Services (and therefore not route the CS call via the home network) if the call is to user in the same visited network. In the case of (a), this will save at one redundant international call leg allowing the media to be transport directly from the visited network to the called party in another (non-home) network. In the case of (b), this will save two redundant call legs, to and from the home network.

It is thus an aim of the present invention to alleviate at least some of

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the disadvantages discussed above. It is another aim of the present invention to offer the possibility for the network to choose how to offer call related services to a CS connected user (e.g. via CS or IMS).

It is another aim of the present invention to provide solutions for transmitting information relating to the UE's and the network's capabilities to support centrally controlled supplementary services, and/or whether the network operator intends to offer centrally controlled services to a HE.

IMS Centralised Services (ICS) sometimes also known as "centralised service control" will allow for consistent presentation of services to all users regardless of whether they are connected via the CS domain or the IMS, and will also facilitate seamless service provision to the user as calls are transferred from one domain to the other.

The task of achieving and supporting centralised control of call related services in itself includes other issues to be addressed such as, for example, the details of the architecture to adopt, how the services are to be delivered and which signalling means are to be used. However, these issues are not addressed directly in this document. Rather, this invention addresses the problem of the HE and/or the Network knowing whether the other supports centralised control or distributed control of call related services. Further it addresses the issue of whether the network operator wishes to provide IMS services centrally to all IMS subscribers regardless of their status (e.g. roaming or not) and that of the network (e.g. due to maintenance). In this way the UE and/or the NW can adapt the call control accordingly. This is particularly important for mid-call services such as Multiparty Calling and Call Hold, but also for the configuration and control of other call related services.

In order to provide centrally controlled services, it is advantageous, and may even be required, that the network knows the capability of the terminal to conilgure and invoke centrally controlled services. Further it is advantageous that the terminal knows whether services are controlled centrally in the IMS, or are controlled in a distributed fashion dependent on

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the domain in which the call is placed. This allows for a better provision of supplementary services.

According to one aspect of the present invention there is provided a method of controlling the provision of supplementary services to a mobile terminal in a communications network including a circuit switched cellular network and an IP Multimedia Network, wherein the control of supplementary services is carried out in the IP Multimedia Network independent of whether a call is carried out via the circuit switched network or whether the IP Multimedia Network and wherein the method includes at least one of the following: i) the terminal transmits information relating to the terminal's capabilities to support centrally controlled supplementary services to the network; or ii) a network element transmits information relating to the network's capabilities or intention to support centrally controlled supplementary services to the terminal.

According to another aspect of the present invention, there is provided a mobile terminal adapted to be used in a communications network including a circuit switched cellular network and an IP Multimedia Network, wherein the control of supplementary services is carried out in the IP Multimedia Network independent of whether a call is carried out via the circuit switched network or whether the IP Multimedia Network, wherein the terminal transmits information relating to the terminal's capabilities to support centrally controlled supplementary services to the network.

According to another aspect of the present invention there is provided a network element for use in a communications network including a circuit switched cellular network and an IP Multimedia Network, wherein the control of supplementary services is carried out in the IP Multimedia Network independent of whether a call is carried out via the circuit switched network or whether the IP Multimedia Network and wherein the network element transmits information relating to the network's capabilities or intention to support centrally controlled supplementary services to the terminal.

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These and other aspects, preferred features and embodiments will be described further, by way of example only, with reference to the accompanying drawings in which: Figs. 1 and 2 are schematic outlines of a mobile communications network, in which the present invention can be incorporated; Fig. 3 is a schematic outline of the architecture of a IMS network; Figs. 4 and 5 are schematic illustrations of the architecture used for supplementary services controlled by the CS domain and the IMS, respectively; Figs. 6A and 6B are schematic illustrations of potential architectures for centrally controlled services; Figs. 7A and 7B are flow chart diagrams illustrating embodiments of the present invention where the UE indicates its capability to support centralised control to the network; Figs. 8A and 8B are flow chart diagrams illustrating embodiments of the present invention where the network indicates its capability or intention to support centralised control to the tilE; and Figs. 9A, 9B, IOA and lOB are flow chart diagrams illustrating embodiments of the present invention where the IJE and the network indicate the capability or intention to support centralised control to the network and to theUE.

As described above presently the Supplementary Services are controlled by either the CS domain or the IMS, depending on whether the call is connected by the CS domain or the II'1S.

Figures 4 and 5 schematically illustrate the architecture used for supplementary services controlled by the CS domain and the IMS, respectively.

As can be seen from Figure 4, calls originating from 1.JE 101 are directed to the remote end via the MSC 103 for supplementary services controlled by the CS domain. This applies both to the control signals and also to the voice or other data.

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Referring now to Figure 5, calls originating from UE 101 are directed via the CSCF 111 to the remote end for supplementary services controlled by the IIMS. Supplementary services are provided by the SIP Telephony Application Server (lAS) 113 or another SIP application server (AS) 115.

Figures 6A & 6B show reference architectures for centrally controlled services, it can be seen from the figures that CS calls are redirected to the ilviS so that a SIP Telephony Application Server (TAS) can provide supplementary services. Thus, the voice or other data for the CS call are directed via the MSC 123 and the MGW 125. The control signals, however are transmitted via the MSC 123, the MGCF 127 and the CSCF 129.

In Figure 6A, the TAS acts as the UE's proxy in the network so that it can provide IMS Services to the CS connected UE as if it were establishing a voice session directly with the IMS.

In Figure 6B, another SIP AS 133, the IMS CS Control Function (ICCF), is used in addition to the TAS 131 to provide a UE proxy function such that the liE's CS connected call appears as an IMS session to the TAS and other Application Servers in the IMS. The telephony services are provided by the TAS in the same way as for other "IIMS" sessions.

In order to provide a centralised (11VIS) control of Supplementary Services regardless of the domain in which the UE is connected, it is advantageous and for certain applications, as for example certain services activated by the UE, it is required that the network knows whether the UE supports centrally controlled services, and that the liE knows whether the network controls services in a centralised fashion.

In the following different embodiments how to implement centrally controlled services will be described.

First Embodiment Figure 7 illustrates flow diagrams for the case that the liE indicates its capability to the network and the network provides services accordingly. In order to provide centrally controlled supplementary services by only the liE

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sending an indication to the network it is required that a network would always provide services controlled in the IMS, or that the provision of ICS in certain circumstances (e.g. when roaming) be subject to operator policy that would not necessarily be signalled at the time of registration or call setup. E.g.

An operator's ICS policy could be provisioned in the UE at the time of supply to the user and stored in lIE non-volatile memory. It may be updated as operator policy changes, e.g. using OMA DM, but the frequency of update would not be expected to be very high.

The UE may send the indication explicitly, or the indication may be implicit e.g. inferred by the network as a result of the way in which the call is established or registration takes place.

Figure 7A is a flow chart diagram illustrating the process of the UE sending its capability indication independently of the call establishment. The process starts in step 202 by the UE registering with the CS domain. If it is determined in step 203 that the UE has send an indicator to the network that it supports centrally controlled supplementary services supplementary services for the user are provided by the IMS (step 205) for any calls from or to this UE which are carried out by the CS domain. If, on the other hand the UE does not send an indicator that it supports centrally controlled supplementary services in step 203, supplementary services for the user are provided in the normal way by the CS domain (step 207) for any calls from or to this lIE which are carried out by the CS domain. It is noted that the UE can send its capability indication at any time between registration and the start of call establishment.

Figure 7B is a flow chart diagram illustrating the process of the UE sending its capability indication as part of the CS call establishment. The process starts in step 212 by the UE registering with the CS domain. In step 213 the UE initiatesa call in the CS domain (step 213). If in step 214 the UE sends an indicator to the network that it supports centrally controlled supplementary services supplementary services for the user are provided by the IMS (step 215). It is noted that steps 213 and 214 are performed in the lIE

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call establishment signalling. If, on the other hand the UE does not send an indicator that it supports centrally controlled supplementary services in step 214, supplementary services for the user are provided in the normal way by the CS domain (step 217) for any calls from or to this UE which are carried out by the CS domain (step 216).

Note that the process of the UE providing its capability during call establishment as in Figure 7B applies only to the case of UE originated calls.

For a terminating call, the network needs to determine whether to route the call via IMS before it could receive any indication from the UE that it supports services controlled it the IMS. Therefore the originating terminal needs to send the indication as described above. It is noted that if centrally controlled services are a subscription based feature and the user has a subscription associated with the home network, then the services will be controlled by that home network. Therefore, it is assumed to that the home IS network (associated with the subscription) will support such services. Thus the UE capable of supporting centrally controlled service always sends it capability indication to the home network. When the home network receives this capability indication it knows to control services for calls centrally.

It is noted that the above described process applies to mobile terminal in the home network rather than a roaming terminal. For a subscription based feature, it may not be possible to re-direct the call to the DvIS in case the terminal is roaming. In the case the terminal is roaming, the UE may need an explicit indication from the network of that centrally controlled services are supported in order to know that the call had been redirected and that services could be provided in this way.

Second Embodiment Figure 8 illustrates the process where only the network sends an indication that it will provide centrally controlled services. In this case the network allows for the UE to invoke services either via the CS domain or via

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the IMS, depending on whether the network element provides the capability or intention indication to the UE.

Figure SA is a flow chart diagram illustrating the process of a network element sending its capability or intention indication independently of the call establishment. The process starts in step 302 by the UE registering with the CS domain. If now the network elements sends an indicator that it will provide centrally controlled supplementary services in step 303, the UE behaves accordingly so that supplementary services for the user are provided by the IMS (step 305) for any calls from or to this UE carried out by the CS domain (step 304). If, on the other hand the network element does not send an indicator that it supports centrally controlled supplementary services in step 303, the IJE uses normal CS procedures and supplementary services for the user are provided in the normal way by the CS domain (step 307) for any calls from or to this UE which are carried out by the CS domain.

Figure 8B is a flow chart diagram illustrating the process of a network element sending its capability or intention indication as part of the CS call establishment. The process starts in step 312 by the IJE registering with the CS domain. In step 313 the UE carries out an originating or terminating call in the CS domain. If in step 314 the network element sends an indicator that it will provide centrally controlled supplementary services, supplementary services for the user are provided by the IMS (step 315).

It is noted that in step 315 supplementary services for the user may either be provided by the [MS for the ongoing call only or, alternatively, for all following calls as well.

Again, steps 313 and 314 are performed in the lIE call establishment signalling. If, on the other hand, the network element does not send an indicator that it will provide centrally controlled supplementary services in step 314, supplementary services for the user are provided in the normal way by the CS domain (step 316).

In order to implement the scenario as discussed above with reference to Figure 8A, the network may know the UE's capability to support centrally r controlled services by means other than an explicitly signalled indication.

This can for example be achieved using the International Mobile Station Equipment Identity (IMEI). In that case, the indication that the network supports centrally controlled services is only be sent to UEs capable of supporting centrally controlled services. A liE therefore knows how to access the centrally controlled. In the scenario discussed above with reference to Figure 8B it is assumed that the network sends the indication to all Ues.

However, the network is able to respond appropriately when providing supplementary services regardless of how the UEs attempt to access services.

Third Embodiment Figure 9 illustrates a further embodiment wherein both HE and NW send capability or intention indications, either independently of the call establishment as in Figure 9A or as part of call establishment as in Figure 9B.

It is noted that the UE could send its capability indication before the NW or vice versa in each of these scenarios.

Figure 9A is a flow chart diagram illustrating the process of both the liE and a network element sending the capability or intention indication independently of the call establishment. The process starts in step 402 by the HE registering with the CS domain. If the liE sends an indicator in step 403 that it supports centrally controlled supplementary services, the process continues in step 404. If the network element sends an indicator that it supports centrally controlled supplementary services in step 404, supplementary services for the user are provided by the IMS (step 406) for any calls from or to this UE which are carried out by the CS domain (step 405). If, on the other hand the network element does not send an indicator that it supports centrally controlled supplementary services in step 404, supplementary services for the user are provided in the normal way by the CS domain (step 408) for any calls from or to this liE which are carried out by the CS domain (step 407). In case that the liE does not send an indicator that it supports centrally controlled supplementary services in step 403,

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supplementary services for the user are again provided by the CS domain (step 408) in the normal way.

Figure 9B is a flow chart diagram illustrating the process of the UIE sending its capability indication as part of the CS call establishment. The process starts in step 412 by the UE registering with the CS domain. In step 413 the UE initiates a call in the CS domain. If in step 414 the UE sends an indicator that it supports centrally controlled supplementary services, the process continues with step 415. If the network element sends an indicator that it supports centrally controlled supplementary services in step 415, supplementary services for the user are provided by the IMS (step 416).

However, if the network element does not send an indicator that it supports centrally controlled supplementary services in step 415, supplementary services for the user are provided in the normal way by the CS domain (step 417) for any calls from or to this UE which are carried out by the CS domain.

Also, if in step 414 the UE sends an indicator that it does not supports centrally controlled supplementary services, supplementary services for the user are provided in the normal way by the CS domain.

It is noted that the indication from the network in step 415 could be sent later in the call establishment signalling than that from the UE in step 414, e.g. after the network had made a decision of how to provision services.

Again the above desired embodiments wherein the UE provides its capability during call establishment is only be applicable in the case of UE originated calls. For a terminating call, the network needs to determine whether to route the call via IMS before it could receive any indication from the UE that it could support services controlled it the IMS. This allows for more optimal routing dependent on UE capability: If the network knows that the UE does not support centrally controlled supplementary services, there is no need to route the call via the IMS. in that case, for a CS incoming call to be terminated in the CS domain, it may not be necessary (if network optimal routing is implemented) to route the user plane for the call via the terminating UIE's home network. Thismay make the call cheaper if the operator does not

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have to incur international call leg rates. It would also mean that fewer transcoding stages were needed is the speech path which would improve Quality of Services (Q0S).

Fourth Embodiment Figure 10 illustrates a yet further embodiment wherein the lIE and a network element send centrally controlled service support indications at different stages of the process.

Figure 1 OA is a flow chart diagram illustrating the process of the IJE sending the capability indication independently of the call establishment, whereas a network element sends the capability or intention indication as part of the call establishment The process starts in step 502 by the UE registering with the CS domain. If the UE sends an indicator in step 503 that it supports centrally controlled supplementary services, the process continues in step 504 by the UE carrying out a originating or terminating call. If now the network element sends an indicator that it supports centrally controlled supplementary services in step 505, supplementary services for the user are provided by the IMS (step 506). If, on the other hand, the network element does not send an indicator that it supports centrally controlled supplementary services in step 504, supplementary services for the user are provided in the normal way by the CS domain (step 508).

In the same way, if the UE does not indicate that it supports centrally controlled supplementary services in step 503, and the UE carries out an originating or terminating call in step 507, supplementary services for the user are provided in the normal way by the CS domain (step 508). It is noted that steps 504, 505 and 507 are carried out in the process of lIE call establishment signalling.

Figure lOB is a flow chart diagram illustrating the process of a network element sending the capability or intention indication independently of the call establishment, whereas the UE sends the capability indication as part of the call establishment The process starts in step 512 by the LIE ( registering with the CS domain. If the network element sends an indicator in step 513 that it supports centrally controlled supplementary services, the process continues in step 514 by the UE initiating a call in the CS domain. If now the UE sends an indicator that it supports centrally controlled supplementary services in step 515, supplementary services for the user are provided by the [MS (step 516). If, on the other hand, the UE does not send an indicator that it supports centrally controlled supplementary services in step 515, supplementary services for the user are provided in the normal way by the CS domain (step 518).

In the same way, if the network element does not indicate that it supports centrally controlled supplementary services in step 513, and the IJE initiates a call in step 517, supplementary services for the user are provided in the normal way by the CS domain (step 518). Again, steps 514, 515 and 517 are carried out in the process of UB call establishment signalling.

Figure 1 OA is perhaps the most advantageous arrangement of all the scenarios given above in that it allows for the network to know the UE capability with respect to support for supplementary services and can then route a UE originated or UE terminated call accordingly via the IMS or via the CS domain. This allows for more optimal signalling and routing of a call.

If it has been possible to route a given call via IMS to provide centrally controlled services, the network provides an indication to the IJE that centrally controlled services are available for the call. This indication can then be used by the UE for example to determine whether domain transfer would be possible during the execution of services. This kind of arrangement.

also helps to ensure backward compatibility for older non-compatible terminals which are not or not fully adapted to support centrally controlled supplementary services. Thus, if no indication of the UE's capability is received by the network, CS calls would always be routed via the CS domain.

hi case that it is the network that does not provide for centrally controlled supplementary services, the UE receives no indication that centrally controlled services are supported for a given call, and does therefore know to a ( access the calls via the CS domain. In the case described above with reference to Figure lOB, the UE knows prior to placing a call whether centrally controlled services are supported, and this may influence both the choice of the domain in which the call is carried out and also the decision whether an indication of it own capabilities is to be sent in this respect.

However, if the UE's capability to support centrally controlled services is only signalled to the network during call establishment it would not be possible for the network to route the call optimally in the case of UE terminated calls.

It is noted that one possibility to implement the above described embodiments that the centrally controlled services are defined in the user's subscription. Is this way the subscription triggers in the CS network (implemented for example using CAMEL) or the initial Filter Criteria (iFC) in IMS will be used to route calls originated/terminated in the CS or IMS respectively to an SiP Telephony Application Server (TAS) so that services can be centrally controlled.

Providing indications from the terminal to the Network As described above, the UE can signal its support of centrally controlled services, either during registration, or at the time of call establishment. The UE may send the indication explicitly, or the indication may be implicit e.g. inferred by the network as a result of the way in which the call is established or registration takes place. In the following different methods of the terminal signalling its ability to support centrally controlled services to the network will be described.

Include information in Classmark 2.

Classmark 2, as defined in the 3GPP specification TS 24.008, is sent in the Location update request and the CM Service Request messages. One spare bit is available in each of the octets 3, 4 and 5, which can be used to include an indication whether the terminal supports centralised control of supplementary services.

In CAMEL 4, Classmark 2 is automatically included in the InitialDP message. Therefore, for redirecting CS originated calls to the IMS for providing services in CAMEL a GSM Service Control Function (gsmSCF) checks whether centrally controlled services are supported and redirects the call accordingly.

Alternatively, the indication could also be provided to the network via the classmark change procedure described in the 3GPP specification IS 44.108 (see section 3.4.10).

Implicitly include information in IMEI of UE The [ME! of the liE could be used by the network to identify whether the UE is capable of supporting centrally provided services. The IMEI is included in InitialDP of CAMEL 4, and also sent during initial liE registration.

Using the registration messages In order to indicate the terminal's capabilities to the network, either all or any of the registration messages in the 3GPP specification TS 24.008 relating to the UB registration at the Network in any of the protocol handshake messages as part of the registration procedures can be used. The registration messages include both the MM registration messages and the GMM registration messages. Registration messages includes both the attach messages and the registration update messages.

Either a new information (IE) can be introduced which are specifically adapted for carrying this indicator or [Es introduced for other purposes can be adapted to carry the above described indicator that centrally controlled services are supported. Additional registration messages to the ICS providing entity may also be utilised to provide an indication of the UE's ability to supports ICS.

Include information in SETUP message Another possibility is to include the indication in the SETUP message sent as part of the Call Control protocol during the call establishment procedure. The 3GPP Call Control protocol is specified in 3GPP TS 24.008.

The indication can for example be included in one of the information elements contained in the SETUP message transmitted by the UE, such as the Call Control Capabilities message (see for example table 10.5.89 of specification TS 24.008). The purpose of this information element is to identify the Call Control Capabilities of the mobile station. The information element is four octets in length. It has one spare bit in octet 3 and four spare bits in octet 4. CAMEL 4 could be modified below the InitialDPArgExtension defined in section 6.1.1 of 29.078 (release 5) to carry this information (i.e. any additional information sent in the SETUP message) towards the gsmSCF that could redirect the call towards the IMS.

All other 24.008 Call Control messages and adaptation of the lEs they carry Alternatively to the SETUP message described above, any of the Call Control messages specified in 3GPP IS 24.008 between the UE and the Network, which is sent prior to the UE going into Call Active state (ie. state U_I 0 as per 3GPP specification IS 24.008), could be used.

However, any message sent after InitialDP had been triggered would require that such information was also carried in ISLTP messages between the MSC and MGCF (and hence into the IMS), which is not guaranteed in the case of a roaming UE. Also, if the call had already been directed to the IMS, some of the benefit of having this information in the network would have been lost in that the network would already be committed to the additional routing (and hence additional subsequent signalling).

Moreover, it is noted, however, that during the Call Active state (ie.

state U_i 0 as per 3GPP IS 24.008) the indication can still be sent or received ( in any of the call control messages specified in TS 24.008 for use within Call Active state (ie. state U_10 as defined in 3GPP TS 24.008) so long as these message carrying the "UE_CenServ_lnd" is sent by the UE and received by the Network before the very first initiation of a supplementary service.

Additionally, any of the JEs carried within all these declared call control messages can be adapted. For instance the "Progress Indicator", the "Facility IE", the "Called Party BCD", the "Called Party Subaddress", the "Calling Party BCD", the Calling Party Subaddress" and any other presently existing or in future specifically introduced JE for this and other purposes could be used or adapted.

Include information in Classmark 3.

A further alternative would be to include the centralised service information in Classmark 3. Although it appears that this solution would be less suitable for carrying the indication and is not presently included in the InitialDP message, it is noted that the indication can be added in the same way as described in relation to including the indication in the SETUP message (e.g. adding below the InitialDPArgExtension) described above.

Signal information directly to TAS via GPRS If the Centralised Service support is a subscription option calls could be redirected to IMS using CAMEL 2. However, this would not allow for the transport of UE Centralised Service support indication. In that case, the indication can be signalled directly to the TEL AS providing Centrally controlled services, via GPRS. The address can for example be provided in the form of a specific dedicated APN. There would need to be some connection between the entity e.g. gsmSCF redirecting the call towards the IMS and the TEL AS receiving the UE indication of support for centrally controlled services. This means that the gsmSCF (or some element providing input control parameters to it) would need to be able to interrogate the TEL ( AS to check the capability of the UE before deciding whether to redirect the call towards the IMS.

Signal information directly to TAS via SMS If Centralised Service support is a subscnption option calls can be redirected to IMS using CAMEL 2, but this does not allow for the transport of UE Centralised Service support indication. Alternatively to signalling via GPRS, the indication can be directly signalled to the TEL AS providing Centrally controlled services via a Short Message Service (SMS). The TEL AS address should be provided so that UE can direct the SMS to it. This can be in the form of an El 64 number. There would need to be some connection between the entity e.g. gsmSCF redirecting the call towards the IMS and the TEL AS receiving the UE indication of support for centrally controlled services as described above. is

Signal information directly to TAS via CS data call Another possibility in case the calls are redirected to IMS using CAMEL 2 is to directly signal the indication to the TEL AS providing Centrally controlled services via a CS data call. The TEL AS address needs to be provided so that the UE can direct the call towards it. This can again be in the form of an E164 number. There would need to be some connection between the entity e.g. gsmSCF redirecting the call towards the IMS and the TEL AS receiving the UE indication of support for centrally controlled services.

Signal information at time of IM registration using Centralised Service feature tag When the IMS is available, the capability of the UE to support centrally controlled services can be indicated through use of a defined feature tag. The tag can for example be named "+g.3gpp.centralised_services" or a similarly indicative name tag. There would need to be some connection 4 4 ( between the entity e.g. gsmSCF redirecting the call towards the [MS and the TEL AS receiving the UE indication of support for centrally controlled services.

Signal information to TAS as part of Mobility Event Package (MEP) When the [MS is available, the capability of the UE to support centrally controlled services can be indicated as part of the SIP Mobility Event Package (MEP). In this case the TAS needs to SUBSCRIBE to the UE information and the UE needs to NOTIFY the TAS if it is capable of supporting centrally controlled supplementary services. The information can be updated and a further NOTIFY message sent if the UE capability changed.

Signal information to TAS using Communication Service ID When the IMS is available, the capability of the UE to support centrally controlled services can be indicated through use of the Communication Service ID. There would need to be some connection between the entity e.g. gsmSCF redirecting the call towards the IMS and the TEL AS receiving the UE indication of support for centrally controlled services Send indication as suffix or prefix to Calling Party BCS Number Information Element as part of call establishment signalling.

As described above, if the Centralised Service support is a subscription option calls can be redirected to [MS using CAMEL 2. However, this does not allow for the explicit transport of UE Centralised Service support indication. In that case, the centralised service support can be indicated by adding a suffix or prefix to the Calling Party BCD Number information element sent in the SETUP message to the network. The indicating is included transparently in the InitialDP message towards gsmSCF and will then be used to determine whether to redirect the call towards the TEL AS or not.

S (

Methods for providing indication from Network to UE In the following different methods of the terminal signalling its ability to support centrally controlled services to the network will be described.

Include information in NAS signalling messages One possibility for the network to indicate support for centrally controlled service is to signal the indication during UE registration in the Location Update Accept message. This message includes the information element Network Feature Support, which has two spare bits available (as described in section 10.5.5.23 of TS 24.008).

Using the registration messages Another possibility is to use any of the registration messages in 3GPP TS 24.008 relating to the UE registration with the Network or any of the protocol handshake messages from the network which are part of the registration procedures. The registration messages include both the MM registration messages and the GMM registration messages. Registration messages includes both the attach messages and the registration update messages.

Alternatively to using the registration messages to transport the indication, any IF in these registration messages can be adapted for this purpose. Also, new lEs can be introduced which are specifically provided for carrying this indicator, or IF introduced for other purposes which can be used.

which are subsequently adapted to carry the indication.

Include information in Progress Indicator IE sent as part of NAS call control messages The Network indication of support for centrally controlled services can also be coded in one of the unspecified values of the Progress Indicator [E (see TS 24.008, Table 10.5.127). The Progress indicator can be included in

S (

the ALERTING, CALL PROCEEDING, CONNECT, PROGESS, and SETUP messages that are (or can be in the case of PROGRESS) sent as part of the Call Control protocol during CS call establishment.

All other 24.008 Call Control messages and adaptation of the lEs they carry In addition to SETUP messages as described above, any of the Call Control messages specified in 3GPP TS 24.008 which are sent between liE and Network prior to the Network going into Call Active state (ie. state N 10 as defined in 3GPP TS 24.008) can be used.

/ It is noted, however, that during the Call Active state (ie. state Nl0 as defined in 3GPP IS 24.008) the indication can still be sent or received in any of the call control messages specified in TS 24.008 for use within Call Active state (ie. state U_10 as defined in 3GPP TS 24.008) so long as these message carrying the "NW_Cen_Serv_Ind" is sent by the network and received by the tiE before the very first initiation of a supplementary service.

Additionally, any of the JEs carried within all these declared call control messages can be adapted. For instance the "Progress Indicator", the "Facility IE", the "Called Party BCD", the "Called Party Subaddress", the "Calling Party BCD", the Calling Party Subaddress" and any other presently existing or in future specifically introduced 1E for this and other purposes could be used or adapted.

Provide information to UE via USSD Another possibility is to send the network indication of support for centrally controlled services to the UE via USSD.

Provide information to UE via SMS The network indication of support for centrally controlled services can also be sent to the liE via SMS.

Provide information to UE via GPRS The network indication of support for centrally controlled services can alternatively be sent to the UE directly using GPRS.

Provide information to UE via OMA DM A OMA Device Management (DM) object can be defined and information about to the network's capability andlor intention to provide centrally controlled services can thus be pushed to the UE as required.

Provide information to UE via OMA CP A OMA Client Provisioning (CP) object can be defined and information about to the NW capability andlor intention to provide centrally controlled services can be pushed to the UE as required.

Provide information to UE via the Ut interface A further possibility is for the UE to use the XCAP protocol to check an XML file at a SIP Application Server containing information about the NW capability and/or intention to provide centrally (IMS) controlled services to 1JE connected via the CS domain.

Send within User-user IE sent as part of NAS call control messages A yet further possibility is to send an indication that centrally controlled services are supported via the User-User IE mapped at the MGCF from an indication sent from the TEL AS. The User-user IE (Table 10.5.131 in TS 24.008) is included in Alerting, Connect, and PROGRESS messages of the Call Control protocol signalling messages used during or as part of CS call establishment. However, it appears that this solution is less advantageous compared to the other solutions discussed above. (

Signal information as part of Mobility Event Package (MEP) When the IMS is available, the capability and or intention of the NW to support centrally controlled services can be indicated as part of the SIP Mobility Event Package (MEP). In this case the UE subscribes to the TAS information and the TAS notifies the IJE if centrally controlled services are available. The in-formation can be updated and a further NOTIFY message sent if the network capability or intention changes for any reason. A reason for a change in the network capability or intention could be for example congestion or maintenance.

Send indication as suffix or prefix to Connect Number Information Element as part of call establishment signalling.

For the mobile originated (MO) call case, it is possible to indicate centrally controlled services support to the liE by adding a suffix or prefix (e.g. *#abc), to the Connected Number information element sent in the final CONNECT message sent to the liE. This can be added to the Connected Number by the TEL AS, or MGCF and forwarded transparently to the VMSC via ISUP signalling (e.g. in ANIvI, or CON messages).

Send indication as suffix or prefix to Calling Party BCD Number information E'ement as part of call establishment signalling.

For the mobile terminated (MT) call case, it is also possible to indicate centrally controlled services support to the liE by adding a suffix or prefix (e.g. *#abc), to the Calling Party BCD Number information element sent in the SETUP message sent towards a terminating Ut. This could be added to the Calling Party Number by the TEL AS or MGCF and forwarded transparently to the VMSC via ISUP signalling (e.g. in JAM message).

Send indication as part of Connected Number sub-address information Element as part of call establishment signalling.

For the MO case, it is also possible to indicate centralised service support to the UE by adding information as described above to the Connected sub-address sent in the CONNECT message towards the UE.

Send indication as part of Calling Party sub-address Information Element as part of call establishment signalling.

For the MT case, it is a further possibility to indicate centralised service support to the UE by adding infoimation as above to the Calling Party BCD sub-address sent in the SETUP message towards the IJE.

Send indication as part of Called Party BCD Number sub-address Information Element as part of call establishment signalling.

For the MT case, it is a yet further possibility to indicate centralised service support to the UE by adding a information as above to the Called Party BCD Number sent in the SETUP message towards the UE.

Send indication as part of Called Party sub-address information Element as part of call establishment signalling.

For the MT case, it is also possible to indicate centralised service support to the UE by adding information as above to the Called Party sub-address sent in the SETUP message towards the UE.

In the above described embodiments centrally controlled services have been described in the context of UMTS. However, it is appreciated that the present invention can alternatively applied to the environment of 2G GERAN, i.e. the AIGb interface, also referred to as Generic Access Network (GAN), and dual mode GSMII-WLAN terminals or other dual mode terminals.

It is to be understood that the above describes embodiments are set out by way of example only, and that many variations or modifications are possible within the scope of the appended claims.

Claims

CLAIMS: 1. A method of controlling the provision of supplementary

services to a mobile terminal in a communications network including a circuit switched cellular network and an IP Multimedia Network, wherein the control of supplementary services is carried out in the IP Multimedia Network independent of whether a call is carried out via the circuit switched network or whether the IP Multimedia Network and wherein the method includes at least one of the following: i) the terminal transmits information relating to the terminal's capabilities to support centrally controlled supplementary services to the network; or ii) a network element transmits information relating to the network element's capabilities or intention to support centrally controlled supplementary services to the terminal.

2. A method according to claim 1, wherein said information is transmitted independent of the call establishment.

3. A method according to claim 1, wherein said information is transmitted as part of the call establishment signalling.

4. A method according to claim 1, wherein the terminal and the network element are transmitting said information.

5. A method according to claim 4, wherein the terminal transmits said information independently of the call establishment and the network element transmits said information as part of the call establishment signalling.

6. A method according to claim 4, wherein the network element transmits said information independently of the call establishment and the terminal transmits said information as part of the call establishment signalling.

7. A method according to any preceding claim, wherein the information in i) is included in classmark
2.

8. A method according to any preceding claim, where in the information in i) is included in a registration message.

9. A method according to any preceding claim, wherein the information in i) is included in a call control message.

10. A method according to any preceding claim, wherein the information in i) is included in a call set-up message.

11. A method according to any preceding claim, wherein the information in i) is included in classmark
3.

12. A method according to any preceding claim, where in the information in i) is included in a registration message.

13. A method according to any preceding claim, wherein the IP Multimedia Subsystem includes an application server and the information in i) is signalled directly to the application server via GPRS.

14. A method according to any preceding claim, wherein the IP Multimedia Subsystem includes an application server and the information in i) is signalled directly to the application server via a short message service. )

15. A method according to any preceding claim, wherein the IP Multimedia Subsystem includes an application server and the information in i) is signalled directly to the application server via a circuit switched data call.

16. A method according to any preceding claim, wherein the IP Multimedia Subsystem includes an application server and the information in i) is signalled to the application server as part of a Mobility Event Package (MEP).

17. A method according to any preceding claim, wherein the information in 1) is signalled at the time of registration with the IP Multimedia subsystem using a centralised service feature tag.

18. A method according to any preceding claim, wherein the IP Multimedia Subsystem includes an application server and the information in i) is signalled to the application server using a communication service ID.

19. A method according to any preceding claim, wherein the information in i) is transmitted as a suffix or prefix to the calling party BCS number information element.

20. A method according to any preceding claim, wherein the information in ii) is included in a Non-Access Stratum (NAS) signalling message.

21. A method according to any preceding claim, wherein the information in ii) is included in a registration message.

22. A method according to any preceding claim, wherein the information in ii) is included in an information element as part of call control messages.

23. A method according to any preceding claim, wherein the information in ii) is included in a progress indicator information element as part of the Non-Access Stratum (NAS) call control messages.

24. A method according to any preceding claim, wherein the information in ii) is transmitted via USSD.

25. A method according to any preceding claim, wherein, the information in ii) is transmitted via a Short Message Service (SMS).

26. A method according to any preceding claim, wherein the information in ii) is transmitted via GPRS.

27. A method according to any preceding claim, wherein the information in ii) is encoded as an Open Mobile Architecture (OMA) Device Management (DM) object.

28. A method according to any preceding claim, wherein the information in ii) is encoded an Open Mobile Archtecture (OMA) Client Provisioning (CP) object.

29. A method according to any preceding claim, wherein the information in ii) is retrieved via the Ut interface.

30. A method according to any preceding claim, wherein the information in ii) is transmitted as part of a Mobility Event Package (MEP).

31. A method according to any preceding claim, wherein the information in ii) is included in an user-user information element as part of the Non-Access Stratum (NAS) call control messages.

32. A method according to any preceding claim, wherein the information in ii) is transmitted as a suffix or prefix to a Connect Number Information Element as part of the call establishment signalling.

33. A method according to any preceding claim, wherein the information in ii) is transmitted as a suffix or prefix to a Calling Party BCN Number Information Element as part of the call establishment signalling.

34. A method according to any preceding claim, wherein the information in ii) is transmitted as part of a Connected Number sub-address Information Element as part of the call establishment signalling.

35. A method according to any preceding claim, wherein the information in ii) is transmitted as part of a calling party sub-address information element as part of the call establishment signalling.

36. A method according to any preceding claim, wherein the information in ii) is transmitted as part of a Called party BCD Number sub-address Information Element as part of the call establishment 37. A method according to any preceding claim, wherein the information in ii) is transmitted as part of a Called Party sub-address Information Element as part of the call establishment 38. A method according to any preceding claim, wherein the information in i) is transmitted implicitly.

39. A method according to claim 38, wherein the information is deduced from the way the call or registration is established.

40. A mobile terminal for use in a communications network adapted to perform the method of any of claims ito 39.

41. A network element adapted to perform the method of any of claims I to39.

42. A mobile terminal adapted to be used in a communications network including a circuit switched cellular network and an IF Multimedia Network, wherein the control of supplementary services is carried out in the IP Multimedia Network independent of whether a call is carried out via the circuit switched network or whether the IP Multimedia Network, wherein the terminal transmits information relating to the terminal's capabilities to support centrally controlled supplementary services to the network.

43. A network element for use in a communications network including a circuit switched cellular network and an IP Multimedia Network, wherein the control of supplementary services is carried out in the IP Multimedia Network independent of whether a call is carried out via the circuit switched network or whether the IP Multimedia Network and wherein the network element transmits information relating to the network element's capabilities or intention to support centrally controlled supplementary services to the terminal.