(56) References cited:

Transcription

1 (19) (12) EUROPEAN PATENT SPECIFICATION (11) EP B1 (4) Date of publication and mention of the grant of the patent: Bulletin 09/49 (21) Application number: (22) Date of filing: (1) Int Cl.: H04W 88/16 (09.01) (86) International application number: PCT/SE02/00177 (87) International publication number: WO 03/070 ( Gazette 03/1) (4) Media gateway for interconnecting mobile access networks, and related method Media-Gateway zum Verbinden von Funkzugangsnetzen und zugehöriges Verfahren Passerelle média pour l interconnexion des réseaux d accés mobiles, et procédé associé (84) Designated Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR IE IT LI LU MC NL PT SE SK TR (6) References cited: EP-A WO-A-01/8086 WO-A-01/1367 () Priority: US (43) Date of publication of application: Bulletin 04/28 (73) Proprietor: TELEFONAKTIEBOLAGET LM ERICSSON (publ) Stockholm (SE) (72) Inventor: NISKA, Hakan S-89 3 Linköping (SE) (74) Representative: Sjöberg, Mats Hakan Ericsson AB Torshamnsgatan Stockholm (SE) EL-HOIYDI A: "Radio Independence in the Network Architecture of the Universal Mobile Telecommunication System" IEEE GLOBECOM 1998, SYDNEY, NSW, AUSTRALIA, vol. 4, 8-12 November 1998, pages , XP ISBN: FYRÖ M ET AL: "Media gateway for mobile networks" ERICSSON REVIEW, no. 4, 00, pages , XP ISSN: cited in the application "Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); Network architecture (3GPP TS version Release 4)" ETSI TS V4.3.0, June 01 (01-06), XP cited in the application EP B1 Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). Printed by Jouve, 7001 PARIS (FR)

2 1 EP B1 2 Description BACKGROUND OF THE PRESENT INVENTION Field of the Invention [0001] The present invention relates generally to thirdgeneration mobile networks, and specifically to media gateways within third-generation mobile networks. Description of Related Art [0002] Third-generation mobile networks are described in the 3G TS (3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Network architecture, Release ) (hereinafter referred to as the Technical Specification). As described in the Technical Specification, third-generation mobile networks logically divide the infrastructure into a Core Network and an Access Network. [0003] The basic Core Network is constituted of circuitswitched nodes, such as Mobile Switching Centers (MSCs), packet-switched nodes, such as General Packet Radio Service support nodes (SGSNs) and control nodes, such as Home Location Registers (HLRs). The basic Access Network is constituted of radio control nodes and radio access nodes. As an example, the radio control nodes may be Base Station Controllers (BSCs) for GSM (Global System for Mobile Communications) radio networks and Radio Network Controller (RNCs) for UMTS (Universal Mobile Telecommunications System) radio networks. As a further example, the radio access nodes may be Base Transceiver Stations (BTSs) for GSM radio networks and Node Bs for UMTS radio networks. [0004] Third-generation mobile networks also partly utilize a layered network architecture. Call control and connectivity, which have traditionally been bundled in telecommunications networks, are now separate layers within the Core Network circuit-switched domain. This separation is achieved by dividing the MSCs into media gateways and network servers. The call control layer is resident in the MSC servers, while the connectivity layer is resident in the Media Gateways. [000] The Media Gateways serve to bridge the different transmission technologies and to add service to enduser connections. The Media Gateways use open interfaces to connect between the Core Network and an Access network. The media gateway control interface (H. 248) facilitates this separation of call control and connectivity layers. Media Gateways are located within the Core Network as an interface to both the Access Networks and to legacy networks, such as the Public Switched Telephone Network (PSTN). [0006] Recent advances in third generation mobile networks have made it possible to have each Media Gateway controlled by a single network server or multiple network servers. For example, as described in an article by Fryo et al. entitled Media gateway for mobile networks, which was published in Ericsson Review No. 4 on Nov., 00, a single Media Gateway may be controlled by more than one network server within the Core Network by the use of Virtual Media Gateways within the Media Gateway. Each Virtual Media Gateway is controlled by one network server, with resources being shared by all of the Virtual Media Gateways. [0007] However, by implementing the Media Gateways within the Core Network, call control and connectivity are not separated in the Access Network. Therefore, Media Gateways cannot be shared between the Access Network and the Core Network. In addition, for calls between Access Networks served by the same MSC server, physical transmission of payloads (e.g., speech or data) between the Access Networks and the Core Network is still required. SUMMARY OF THE INVENTION [0008] The present invention is directed to a Media Gateway and a method for using H.248 Media Gateways within the whole network (both Core Network and Access Network). The H.248 Access Network Media Gateways enable the separation of the call control and connectivity layers within the Access Network. Each H.248 Media Gateway is capable of serving one or more radio control servers of the Access Network and one or is capable of serving one or more radio control servers of the Access Network and one or more network servers of the Core Network. In addition, pools of devices (e.g., transcoders) can be shared between the radio control servers and network servers. [0009] Furthermore, the Media Gateways can provide H.248 Virtual Gateways capable of serving the radio control servers within two or more Access Networks and the network servers within the Core Network. In implementation, one or more H.248 Media Gateways can be placed at strategic locations at the border between two or more Access Networks. Therefore, physical transmission of payloads (e.g., speech or data) between the two different Access Networks is normally not required, logically defined only as interface terminations between the Virtual Gateways of the radio control servers and the network servers. [00] Furthermore, the Media Gateways within the Access Network can provide H.248 Virtual Gateways capable of serving the radio control servers within one or more Access Networks and the network servers within the Core Network. In implementation, one or more H.248 Media Gateways can be placed at strategic locations at the border between one or more Access Networks and an external network, such as the PSTN. Calls to PSTN subscribers can then normally be made as local PSTN calls. 2

3 3 EP B1 4 BRIEF DESCRIPTION OF THE DRAWINGS [0011] The disclosed invention will be described with reference to the accompanying drawings, which show important sample embodiments of the invention and which are incorporated in the specification hereof by reference, wherein: FIGURE 1 is a block diagram illustrating a prior art third generation mobile network; FIGURE 2 is a block diagram illustrating the Access Network architecture in accordance with embodiments of the present invention; FIGURE 3 is a block diagram of an exemplary Media Gateway including one or more Virtual Media Gateways for interfacing with Access Network servers and Core Network servers, in accordance with embodiments of the present invention; FIGURE 4 is a block diagram of the components of the Media Gateway and Virtual Media Gateways shown in FIGURE 3; and FIGURE is an example of a call connection between two Access Networks using the Virtual Media Gateways shown in FIGURES 3 and 4. DETAILED DESCRIPTION OF THE EXEMPLARY EM- BODIMENTS [0012] The numerous innovative teachings of the present application will be described with particular reference to the exemplary embodiments. However, it should be understood that this class of embodiments provides only a few examples of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily delimit any of the various claimed inventions. Moreover, some statements may apply to some inventive features but not to others. [0013] FIGURE 1 shows a conventional third-generation mobile network 0, in which the call control and connectivity of the Core Network 1 have been separated into different layers. Within the third-generation mobile network 0, the switching fabric is removed from the MSC and placed in a Media Gateway (MGW) a. Thus, the MSC is divided internally, creating a MSC server 14 and a MGW a. Likewise, the Gateway MSC (GM- SC) is divided internally, creating a GMSC server 1 and a MGW b. In addition, for packet data services, the serving General Packet Radio Service (GPRS) support node (SGSN) and the Gateway GPRS Support Node (GGSN) are both divided internally, creating a SGSN server 16, a GGSN server 17 and respective MGWs c and d for the SGSN server 16 and GGSN server 17. [0014] The MGWs a-d provide for interworking between an Access Network, such as the Universal Terrestrial Radio Access Network (UTRAN) 10a or GSM network 10b, and the Core Network 1. For example, MGWs a and b provide an interface for handling circuit-switched traffic between the Access Network 10a or 10b and an external network, such as the PSTN 160a. Likewise, MGWs c and d provide an interface for handling packet-switched traffic between the Access Network 10a or 10b and an external network, such as the Internet 160b. [001] The MGWs a-d each have an H.248 control interface Mc that provides the signaling connection for user traffic control between the servers and their respective MGWs a-d. Signaling connections between the servers and signaling connections between the servers and the Access Networks 10a and 10b are not shown in FIGURE 1, but the MGW=s a-d may route this signaling from the physical interfaces directly to the servers The MGWs a-d also includes a number of devices for various services, such as conference calling, announcements and transcoders (e.g., voice coders). In addition, MGWs a and b are interconnected with other MGWs for circuit-switched payload transmission between MSC/ GMSC servers via the Nb interface. [0016] As an example, in FIGURE 1, a circuit-switched call between the UTRAN Access Network 10a and the PSTN 160a is interconnected by MGWs a and b. Speech originated by a mobile terminal (not shown) in wireless communication with a Node B 2a of the UTRAN Access Network 10a is transmitted to the Radio Network Controller (RNC) a of a Radio Network System (RNS) via the lubis interface. [0017] Thereafter, circuit-switched payloads are transmitted from the RNC a over the Iu-CS interface to the MGW a. The MGW a processes the payloads and provides the interface to the PSTN 160a via MGW b. The MSC server 14 and the GMSC server 1 provide the user traffic control for the circuit-switched call by controlling their respective MGWs a and b via H.248 control paths Mc. The MGWs a and b interconnect for routing of the payloads via interface Nb. It should be noted that the Iur interface connects two RNC=s (only one of which is illustrated in FIGURE 1). [0018] As another example, within FIGURE 1, a packet-switched call between the GSM Access Network 10b and the Internet 160b is interconnected by MGWs c and d. Packet data originated by a mobile terminal (not shown) in wireless communication with a Base Transceiver Station (BTS) 2b of the GSM Access Network 10b is transmitted to the Base Station Controller (BSC) b of a Base Station System (BSS) via the Abis interface. [0019] Thereafter, packet-switched payloads are transmitted from the BSC b over the Gb interface to the MGW c. The MGW c processes the payloads and provides the interface to the Internet 160b via the Gp interface. The SGSN server 16 and the GGSN server 17 provide the user traffic control for the packet-switched call by controlling their respective MGWs c and d via H.248 control paths Mc, as described above. The MGWs c and d interconnect for routing of payloads 3

4 EP B1 6 via the Gn interface. [00] As can be seen in FIGURE 1, with conventional third-generation mobile networks, the call control and connectivity layers are not separated within the Access Network 10a and 10b. Therefore, Media Gateways a-d cannot be shared between the Access Network 10a and 10b and the Core Network 1. In a new Access Network architecture, as shown in FIGURE 2 and in accordance with exemplary embodiments of the present invention, a new type of MGW (illustrated as 0a and 0b) can be implemented in each Access Network 10a and 10b, respectively, to serve as the interface directly between the Access Network 10a and 10b and the Core Network (not shown in FIGURE 2). [0021] Therefore, to separate call control and connectivity, in accordance with embodiments of the present invention, the RNC and BSC are divided internally, creating an RNC server a and an MGW 0a and a BSC server b and an MGW 0b. The MGWs 0a and 0b provide the Iubis and Abis interfaces to the base stations (Node B 2a and BTS 2b, respectively) of the two Access Networks 10a and 10b. In addition, MGWs 0a and 0b provides the A or Iu-Cs interfaces, respectively, to the Core Network (not shown) for circuitswitched traffic, and the Gb or Iu-Ps interfaces, respectively, to the Core Network for packet-switched traffic. The radio servers (e.g., RNC server a and BSC server b) provide the user traffic control for packet-switched and circuit-switched calls by controlling their MGWs 0a and 0b via respective H.248 control paths Mc. Signaling connections between radio servers and the base stations, and signaling connections between the radio servers and the Core Network are not shown in FIGURE 2, but the MGWs 0a and 0b may route this signaling from the physical interfaces directly to the servers. [0022] In addition, in conventional third-generation mobile networks, as shown in FIGURE 1, calls must always be routed through the Core Network 1 even when the call is between two Access Networks 10a and 10b served by the same MSC server 14. In order to more efficiently manage the load within the Core Network 1, referring now to FIGURE 3, this new type of MGW 0 can also provide the interface between two or more Access Networks 10a or 10b and between an Access Network 10a or 10b and an external network, such as the PSTN or Internet. Therefore, the MGW 0 can be controlled by more than one server via the use of Virtual Media Gateways 2. As shown in FIGURE 3, the RNC server a, BSC server b, MSC server 14, GMSC server 1 and SGSN server 16 can all interconnect with the MGW 0 for control of payload traffic (circuit-switched and packet-switched). [0023] In order for each server (radio and network) to control payloads routed between an Access Network and an external network, the MGW 0 maintains a separate Virtual MGW 2 for each server. For example, to perform the protocol conversion between the two Access Networks 10a and 10b, the RNC server a and BSC server b each control separate Virtual MGWs 2a and 2b, respectively, within the MGW 0. In addition, the MSC server 14, GMSC server 1 and SGSN server 16 each maintain control of a Virtual MGW 2c, 2d and 2e, respectively, within the MGW 0 for interconnecting with the legacy networks (e.g., PSTN/PLMN and Internet). [0024] Separate H.248 interfaces Mc between the MGW 0 and the servers provide the user traffic control, while separate physical connections (e.g., Gn interface, Gp interface, PSTN interface, Nb interface, Abis interface, Iubis interface and Iur interface) to each of the Access Networks 10 and the legacy networks 160 provide the payload connectivity. Therefore, physical transmission of payloads between the RNC a, BSC b and the Core Network is no longer required, logically being defined only as interface terminations between the Virtual MGWs (i.e., between Virtual MGW 2a and Virtual MGW 2c, between Virtual MGW 2a and Virtual MGW 2e, between Virtual MGW 2b and Virtual MGW 2c, and between Virtual MGW 2b and 2e). In addition, resources (e.g., transcoders) in the MGW 0 can be shared between the Virtual MGWs 2. Furthermore, one or more of such MGWs 0 may be placed at strategic locations at the borders between two or more Access Networks 10a and 10b to provide the connectivity between multiple Access Networks 10a and 10b and multiple radio servers a and b within each of the Access Networks 10a and 10b. [002] It should be understood that any type of Access Network 10 and any number of Access Networks 10 can be served by the MGW 0 shown in FIGURE 3. As an example, in the MGW 0 of FIGURE 3, the GSM Access Network 10b and the UTRAN Access Network 10a are interconnected via the MGW 0. The MGW 0 provides the connectivity between the GSM Access Network 10b and the UTRAN Access Network 10a by converting between protocols used in each of the Access Networks 10a and 10b. [0026] For example, the GSM Access Network 10b currently uses compressed speech transmitted over circuits. In the future, the GSM Access Network 10b may transmit speech as IP packets. However, the UTRAN Access Network 10a uses compressed speech transmitted over an ATM network. The MGW 0 allows speech to be easily routed between the two Access Networks 10a and 10b by converting circuit-switched compressed speech into ATM-switched compressed speech and vice-versa. [0027] A detailed view of the functional architecture of the MGW 0 and Virtual MGWs 2 is shown in FIGURE 4. All Virtual MGWs 2 are capable of sharing resource components (e.g., transcoders) available from a resource component database 0. However, resource components can also be preconfigured, by identity and type, for any Virtual MGW 2 and stored within the resource component database 0. [0028] An H.248 message received at the MGW 0 4

5 7 EP B1 8 is processed by an H.248 message handler 42 for the appropriate Virtual MGW 2. A connection handler 4 within the Virtual MGW 2 establishes a connection between the Virtual MGW 2 and another Virtual MGW (not shown) and allocates available resource components according to the resource component database 0. [0029] Resource components (e.g., transcoders) are composed of payload framing components a and payload stream components b. Payload framing components a terminate different protocol layers (e.g., IP, user datagram protocol (UDP) and real-time transport protocol (RTP))and convert the protocols between the different Access Networks or between an Access Network and the Core Network. Payload stream components b process the actual speech or data. [00] FIGURE illustrates a call between one Access Network 10b (i.e., GSM) and another Access Network 10a (i.e., UTRAN) using the Virtual MGWs 2 shown in FIGURES 3 and 4. During the establishment phase of a mobile originated call within the GSM Access Network 10b, the calling mobile terminal a sends a call set up request and the B-number of a called mobile terminal b to the MSC server 14. The call control signaling between the BTS 2b, BSC server b and MSC server 14 are well-known in the art, and will not be described in detail herein. [0031] Upon receipt of the call setup request, the MSC server 14 reserves a connection point A in the Virtual MGW 2c. The connection point A is associated with the Virtual MGW 2b for the BSC server b. The MSC server 14 also instructs the BSC server b to establish a connection for the calling mobile terminal a to point A in Virtual MGW 2c. In response, the BSC server b allocates a speech channel to the calling mobile terminal a and orders the Virtual MGW 2b to connect the allocated speech channel to point A in the Virtual MGW 2c. [0032] To connect the call to the called mobile terminal b, the MSC server 14 analyzes the B-number of the called mobile terminal b and locates the called mobile terminal b (i.e., by interrogating a Home Location Register). Upon determining that the called mobile terminal b is registered in the Visitor Location Register (VLR) of the MSC server 14 and within the UMTS Access Network 10a, the MSC server 14 pages the called mobile terminal b in the UMTS Access Network 10a. When the called mobile terminal b responds to the page, the MSC server 14 selects a connection point B in the Virtual MGW 2c that is associated with the Virtual MGW 2a. [0033] Thereafter, the MSC server 14 requests the RNC server a to establish a connection for the called mobile terminal b to point B in Virtual MGW 2c. In response, the RNC server a allocates a speech channel to the called mobile terminal b and orders the Virtual MGW 2a to connect the allocated speech channel to point B in the Virtual MGW 2c. [0034] The connection handler within the Virtual MGW c of the MSC server 14 establishes a connection between the Virtual MGW 2b of the BSC server b and the Virtual MGW 2a of the RNC server a. Once the connection is established, payloads can be transmitted between the BTS 2b and the MGW 0 over the Abis interface and between the MGW 0 and the Node B 2a over the Iubis interface to connect the call between the calling mobile terminal a and the called mobile terminal b. The call is controlled via the H.248 interfaces of the RNC server a, the BSC server b and MSC server 14. Advantageously, resources (e.g., transcoders) can be shared between the two Access Networks 10a and 10b. [003] As will be recognized by those skilled in the art, the innovative concepts described in the present application can be modified and varied over a wide range of applications. Accordingly, the scope of patented subject matter should not be limited to any of the specific exemplary teachings discussed, but is instead defined by the following claims. Claims 1. A media gateway (0) for interconnecting two or more mobile access networks (10a, 10b), comprising: a first virtual media gateway (2a) associated with a first one (10a) of said two or more mobile access networks, said first virtual media gateway (2a) having an H.248 interface to a radio server (a) within said first mobile access network (10a) for handling the user traffic control and a physical connection to at least one base station (2a) within said first access network (10a) for handling the call connectivity to and from said first access network (10a); a second virtual media gateway (2b) associated with a second one (10b) of said two or more mobile access networks, said second virtual media gateway (2b) having an H.248 interface to a radio server (b) within said second mobile access network (10b) for handling the user traffic control and a physical connection to at least one base station (2b) within said second access network (10b) for handling the call connectivity to and from said second access network (10b); and a third virtual media gateway (2c-e) having an H.248 interface to at least one core network server (14, 1, 16) within a core network (1) for handling the connectivity control between said two or more mobile access networks (10a, 10b) and said core network (1), said first (2a) and second (2b) virtual media gateways being interconnected via said third virtual media gateway (2c-e).

6 9 EP B1 2. The media gateway of Claim 1, wherein each of said virtual media gateways has a connection handler therein capable of establishing a connection between said first virtual media gateway and said second virtual media gateway via said third virtual media gateway in order to convert payloads between said virtual media gateways for a call. 3. The media gateway of Claim 2, further comprising: a database housing resource components, said virtual media gateways being capable of sharing said resource components within said database. 4. The media gateway of Claim 3, wherein said connection handlers are further capable of allocating available ones of said resource components from said database for said call. 1 allocating resource components from a database (0) within said media gateway (0) for said call connection; and establishing a physical connection between a base station (2a) of said first mobile access network (10a) and said first virtual media gateway (2a) and between said third virtual media gateway (2b) and a base station (2b) of said second mobile access network (10b) for transmission of payloads during said call connection. 11. The method of Claim, wherein said step of establishing a connection between said first and second virtual media gateways comprises: reserving a connection point in said second virtual media gateway associated with said first virtual media gateway.. The media gateway of Claim 3, wherein said resource components comprise one or more transcoders. 6. The media gateway of Claim 3, wherein said resource components comprise payload framing components and payload stream components The method of Claim 11, wherein said step of establishing a connection between said second and third virtual media gateways comprises: reserving a connection point in said second virtual media gateway associated with said third virtual media gateway. 7. The media gateway of Claim 3, wherein at least one of said two or more access networks maintains separate resource components within said database for use by said respective first or second virtual media gateway. 13. The method of Claim, wherein said step of allocating said resource components further comprises: sharing said resource components between said virtual media gateways. 8. The media gateway of Claim 1, wherein one of said two or more access networks is a Universal Terrestrial Radio Access Network. 9. The media gateway of Claim 1, wherein one of said two or more access networks is a Global System for Mobile Communications Network The method of Claim, wherein said step of allocating said resource components further comprises: allocating separate ones of said resource components for said first and third virtual media gateways.. A method for establishing a call connection between a first mobile access network (10a) and a second mobile access network (10b) interconnected via a media gateway according to claim 1 comprising: receiving a message at a network server (14, 1, 16) within a core network (1) to setup said call connection; establishing a logical connection between a first virtual media gateway (2a) associated with said first mobile access network (10a) and a second virtual media gateway (2c-e) controlled by said network server (14, 1, 16); establishing a logical connection between said second virtual media gateway (2c-e) and a third virtual media gateway (2b) associated with said second mobile access network (10b); 4 0 Patentansprüche 1. Media-Gateway (0), um zwei oder mehr Mobilzugangsnetze (10a, 10b) zusammenzuschalten, umfassend: ein erstes virtuelles Media-Gateway (2a), das mit einem ersten (10a) der zwei oder mehr Mobilzugangsnetze assoziiert ist, wobei das erste virtuelle Media-Gateway (2a) eine H.248- Schnittstelle zu einem Funkserver (a) innerhalb des ersten Mobilzugangsnetzes (10a) hat, um die Benutzerverkehrssteuerung zu handhaben, und eine physikalische Verbindung zu mindestens einer Basisstation (2a) innerhalb des ersten Zugangsnetzes (10a), um die Anrufkonnektivität zum und vom ersten Zugangsnetz 6

7 11 EP B1 12 (10a) zu handhaben; ein zweites virtuelles Media-Gateway (2a), das mit einem zweiten (10b) der zwei oder mehr Mobilzugangsnetze assoziiert ist, wobei das zweite virtuelle Media-Gateway (2b) eine H.248-Schnittstelle zu einem Funkserver (b) innerhalb des zweiten Mobilzugangsnetzes (10b) hat, um die Benutzerverkehrssteuerung zu handhaben, und eine physikalische Verbindung zu mindestens einer Basisstation (2b) innerhalb des zweiten Zugangsnetzes (10b), um die Anrufkonnektivität zum und vom zweiten Zugangsnetz (10b) zu handhaben; und ein drittes virtuelles Media-Gateway (2c-e) mit einer H.248-Schnittstelle zu mindestens einem Kernnetzserver (14, 1, 16) innerhalb eines Kernnetzes (1), um die Konnektivitätssteuerung zwischen den zwei oder mehr Mobilzugangsnetzen (10a, 10b) und dem Kernnetz (1) zu handhaben, wobei das erste (2a) und das zweite (2b) virtuelle Media-Gateway über das dritte virtuelle Media-Gateway (2c-e) zusammengeschaltet sind. 2. Media-Gateway nach Anspruch 1, worin jedes der virtuellen Media-Gateways darin einen Verbindungshandler hat, der befähigt ist, eine Verbindung zwischen dem ersten virtuellen Media-Gateway und dem zweiten virtuellen Media-Gateway über das dritte virtuelle Media-Gateway herzustellen, um Nutzdaten zwischen den virtuellen Media-Gateways für einen Anruf zu konvertieren. 3. Media-Gateway nach Anspruch 2, außerdem umfassend: eine Ressourcenkomponenten enthaltende Datenbank, wobei die virtuellen Media-Gateways befähigt sind, die Ressourcenkomponenten in der Datenbank gemeinsam zu nutzen. 4. Media-Gateway nach Anspruch 3, worin die Verbindungshandler außerdem befähigt sind, verfügbar der Ressourcenkomponenten aus der Datenbank für den Anruf zuzuweisen.. Media-Gateway nach Anspruch 3, worin die Ressourcenkomponenten einen oder mehrere Transcoder umfassen. 6. Media-Gateway nach Anspruch 3, worin die Ressourcenkomponenten Nutzdaten-Rahmenbildungskomponenten und Nutzdatenstromkomponenten umfassen Media-Gateway nach Anspruch 3, worin mindestens eines der zwei oder mehr Zugangsnetze zur Verwendung durch das jeweilige erste oder zweite virtuelle Media-Gateway getrennte Ressourcenkomponenten in der Datenbank unterhält. 8. Media-Gateway nach Anspruch 1, worin eines der zwei oder mehr Zugangsnetze ein UTRAN (Universal Terrestrial Radio Access Network) ist. 9. Media-Gateway nach Anspruch 1, worin eines der zwei oder mehr Zugangsnetze ein GSM(Global System for Mobile Communications)-Netz ist.. Verfahren zum Herstellen einer Anrufverbindung zwischen einem ersten Mobilzugangsnetz (10a) und einem zweiten Mobilzugangsnetz (10b), die über ein Media-Gateway nach Anspruch 1 zusammengeschaltet sind, umfassend: Empfangen einer Nachricht auf einem Netzserver (14, 1, 16) in einem Kernnetz (1), um die Anrufverbindung aufzubauen; Herstellen einer logischen Verbindung zwischen einem ersten virtuellen Media-Gateway (2a), das mit dem ersten Mobilzugangsnetz (10a) assoziiert ist, und einem zweiten virtuellen Media-Gateway (2c-e), das vom Netzserver (14, 1, 16) gesteuert wird; Herstellen einer logischen Verbindung zwischen dem zweiten virtuellen Gateway (2c-e) und einem dritten virtuellen Media-Gateway (2b), das mit dem zweiten Mobilzugangsnetz (10b) assoziiert ist; Zuweisen von Ressourcenkomponenten aus einer Datenbank (0) im Media-Gateway (0) für die Anrufverbindung; und Herstellen einer physikalischen Verbindung zwischen einer Basisstation (2a) des ersten Mobilzugangsnetzes (10a) und dem ersten virtuellen Media-Gateway (2a) und zwischen dem dritten virtuellen Media-Gateway (2b) und einer Basisstation (2b) des zweiten Mobilzugangsnetzes (10b) zur Übertragung von Nutzdaten während der Anrufverbindung. 11. Verfahren nach Anspruch, worin der Schritt des Herstellens einer Verbindung zwischen dem ersten und dem zweiten virtuellen Media-Gateway umfasst: Reservieren eines Verbindungspunkts im zweiten virtuellen Media-Gateway, der mit dem ersten virtuellen Media-Gateway assoziiert ist. 12. Verfahren nach Anspruch 11, worin der Schritt des Herstellens einer Verbindung zwischen dem zweiten und dem dritten virtuellen Media-Gateway umfasst: Reservieren eines Verbindungspunkts im zweiten virtuellen Media-Gateway, der mit dem dritten virtuellen Media-Gateway assoziiert ist. 7

8 13 EP B Verfahren nach Anspruch, worin der Schritt des Zuweisens der Ressourcenkomponenten außerdem umfasst: gemeinsames Nutzen der Ressourcenkomponenten zwischen den virtuellen Media-Gateways. 14. Verfahren nach Anspruch, worin der Schritt des Zuweisens der Ressourcenkomponenten außerdem umfasst: Zuweisen von separaten der Ressourcenkomponenten für das erste und das dritte virtuelle Media-Gateway. Revendications 1 2. Passerelle multimédia selon la revendication 1, dans laquelle chacune desdites passerelles multimédia virtuelles présente un gestionnaire de connexion apte à établir une connexion entre ladite première passerelle multimédia virtuelle et ladite deuxième passerelle multimédia virtuelle par le biais de ladite troisième passerelle multimédia virtuelle en vue de convertir des données utiles entre lesdites passerelles multimédia virtuelles pour un appel. 3. Passerelle multimédia selon la revendication 2, comportant en outre : une base de données hébergeant des composantes de ressources, lesdites passerelles multimédia virtuelles étant aptes à partager lesdites composantes de ressources au sein de ladite base de données. 1. Passerelle multimédia (0) destinée à interconnecter deux réseaux d accès mobile ou plus (10a, 10b), comportant : une première passerelle multimédia virtuelle (2a) associée à un premier (10a) desdits deux réseaux d accès mobile ou plus, ladite première passerelle multimédia virtuelle (2a) présentant une interface H.248 au niveau d un serveur radio (a) au sein dudit premier réseau d accès mobile (10a) en vue de traiter la commande de trafic utilisateur, et une connexion physique à au moins une station de base (2a) au sein dudit premier réseau d accès (10a) permettant de traiter la connectivité d appel vers et depuis ledit premier réseau d accès (10a) ; une deuxième passerelle multimédia virtuelle (2b) associée à un second (10b) desdits deux réseaux d accès mobile ou plus, ladite deuxième passerelle multimédia virtuelle (2b) présentant une interface H.248 au niveau d un serveur radio (b) au sein dudit second réseau d accès mobile (10b) en vue de traiter la commande de trafic utilisateur, et une connexion physique à au moins une station de base (2b) au sein dudit second réseau d accès (10b) pour traiter la connectivité d appel vers et depuis ledit second réseau d accès (10b) ; et une troisième passerelle multimédia virtuelle (2c-e) présentant une interface H.248 au niveau d au moins un serveur de réseau fédérateur (14, 1, 16) au sein d un réseau fédérateur (1) en vue de traiter la commande de connectivité entre lesdits deux réseaux d accès mobile ou plus (10a, 10b) et ledit réseau fédérateur (1), lesdites première (2a) et deuxième (2b) passerelles multimédia virtuelles étant interconnectées par le biais de ladite troisième passerelle multimédia virtuelle (2c-e) Passerelle multimédia selon la revendication 3, dans laquelle lesdits gestionnaires de connexion sont en outre aptes à affecter des composantes disponibles parmi lesdites composantes de ressources à partir de ladite base de données pour ledit appel.. Passerelle multimédia selon la revendication 3, dans laquelle lesdites composantes de ressources comportent un ou plusieurs transcodeurs. 6. Passerelle multimédia selon la revendication 3, dans laquelle lesdites composantes de ressources comportent des composantes d encadrement de données utiles et des composantes de flux de données utiles. 7. Passerelle multimédia selon la revendication 3, dans laquelle au moins l un desdits deux réseaux d accès ou plus maintient des composantes de ressources distinctes au sein de ladite base de données en vue d une utilisation par ladite première ou ladite deuxième passerelle multimédia virtuelle respective. 8. Passerelle multimédia selon la revendication 1, dans laquelle l un desdits deux réseaux d accès ou plus est un réseau d accès radio terrestre universel. 9. Passerelle multimédia selon la revendication 1, dans laquelle l un desdits deux réseaux d accès ou plus est un réseau de système mondial de communication avec les mobiles.. Procédé destiné à établir une connexion d appel entre un premier réseau d accès mobile (10a) et un second réseau d accès mobile (10b) interconnectés par le biais d une passerelle multimédia selon la revendication 1, comportant les étapes ci-après consistant à : 8

9 1 EP B1 16 recevoir un message au niveau d un serveur de réseau (14, 1, 16) au sein d un réseau fédérateur (1) en vue d établir ladite connexion d appel ; établir une connexion logique entre une première passerelle multimédia virtuelle (2a) associée audit premier réseau d accès mobile (10a) et une deuxième passerelle multimédia virtuelle (2c-e) commandée par ledit serveur de réseau (14, 1, 16) ; établir une connexion logique entre ladite deuxième passerelle multimédia virtuelle (2ce) et une troisième passerelle multimédia virtuelle (2b) associée audit second réseau d accès mobile (10b) ; affecter des composantes de ressources à partir d une base de données (0) au sein de ladite passerelle multimédia (0) pour ladite connexion d appel ; et établir une connexion physique entre une station de base (2a) dudit premier réseau d accès mobile (10a) et ladite première passerelle multimédia virtuelle (2a), et entre ladite troisième passerelle multimédia virtuelle (2b) et une station de base (2b) dudit second réseau d accès mobile (10b), en vue d une transmission de données utiles au cours de ladite connexion d appel. 1 2 ressources comporte en outre l étape consistant à : affecter des composantes de ressources individuelles parmi lesdites composantes de ressources pour lesdites première et troisième passerelles multimédia virtuelles. 11. Procédé selon la revendication, dans lequel l étape consistant à établir une connexion entre lesdites première et deuxième passerelles multimédia virtuelles comporte l étape consistant à : réserver un point de connexion dans ladite deuxième passerelle multimédia virtuelle associée à ladite première passerelle multimédia virtuelle Procédé selon la revendication 11, dans lequel l étape consistant à établir une connexion entre lesdites deuxième et troisième passerelles multimédia virtuelles comporte l étape consistant à : réserver un point de connexion dans ladite deuxième passerelle multimédia virtuelle associée à ladite troisième passerelle multimédia virtuelle Procédé selon la revendication, dans lequel l étape consistant à affecter lesdites composantes de ressources comporte en outre l étape consistant à : 0 partager lesdites composantes de ressources entre lesdites passerelles multimédia virtuelles. 14. Procédé selon la revendication, dans lequel l étape consistant à affecter lesdites composantes de 9

10 EP B1

11 EP B1 11

12 EP B1 12

13 EP B1 13

14 EP B1 REFERENCES CITED IN THE DESCRIPTION This list of references cited by the applicant is for the reader s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard. Non-patent literature cited in the description Fryo et al. Media gateway for mobile networks. Ericsson Review, November 00 [0006] 14