WO2000065802A1

WO2000065802A1 - Virtual numbering plan for inter-operability between heterogeneous networks

Info

Publication number: WO2000065802A1
Application number: PCT/SE2000/000695
Authority: WO
Inventors: Lila Madour; Shabnam Sultana
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 1999-04-28
Filing date: 2000-04-11
Publication date: 2000-11-02
Also published as: JP2002543677A; CA2371555C; EP1173964A1; CN1359582A; CA2371555A1; CN1171479C; AU4444100A

Abstract

The present invention provides a multi-protocol addressing scheme that allows for full inter-operability between networks in a heterogeneous environment. According to exemplary embodiments, a system and method is provided for statically or dynamically assigning to a user requesting access a virtual number parameter. The virtual number parameter is a generic routing address that provides all possible routable addresses (e.g., IP, ATM, X.25, user@realm, E.164, etc.) compatible to the routing technology supported by the system serving the particular user. Through the use of this virtual number parameter, call setup between heterogeneous networks is facilitated.

Description

VIRTUAL NUMBERING PLAN FOR INTER-OPERABILITY BETWEEN HETEROGENEOUS NETWORKS

BACKGROUND The present invention relates generally to communication systems and, more particularly, to techniques and structures for establishing a connection in a cellular environment comprising both telecommunication and data communication networks. The Global System for Mobile (GSM) communications describes a European standard for communications and the corresponding Public Land Mobile Network (PLMN) which is intended to provide uniformity so that users can access communication systems throughout any GSM system with minimal equipment compatibility problems. As such, PLMN telecommunication systems have provided mobile subscribers with the ability to freely travel within the GSM system and utilize the mobile services provided therein. Figure 1 illustrates an exemplary conventional wireless GSM telecommunications network. Conventional wireless GSM telecommunications networks generally include base transceiver stations (BTSs), base station controllers (BSCs), Mobile Switching Centers (MSCs) equipped with Visitor Location Registers (NLRs), and Home Location Registers (HLRs) having Authentication Centers (AuCs). Each BTS provides communications to one or more mobile stations (MSs) located in a respective cell or zone of the wireless network. A BSC controls the operation of one or more BTSs. The BSCs are interconnected with the MSCs that route information to an intended destination (e.g. , a Public Switched Telephone Network (PSTN)). Each MSC is associated with a HLR and VLR. The HLR stores location information and subscriber data that defines the services authorized for each mobile station. The VLR stores subscriber data for those mobile stations currently located in the service area of the corresponding MSC. Additional information regarding conventional wireless telecommunications networks is available in U.S. Patent No. 5,862,481 to Kulkarni et al. and U.S. Patent No. 5,867,788 to Joensuu both of which are expressly incorporated by reference herein.

Under the conventional telecommunications approach, when a mobile station travels into a new MSC coverage area or is activated, the mobile station first attempts to register with the serving MSC. This registration process is accomplished by the mobile station transmitting an associated identifier (e.g., the International Mobile Subscriber Identity (IMSI) number) to the serving MSC. The IMSI, as one skilled in the art will appreciate, is mapped to the MSISDN of the mobile station by the system. The serving MSC, using this information, then communicates with the particular HLR that stores subscriber information for the requesting mobile station in order to inform the HLR of the mobile station's new location and to retrieve subscriber information for the mobile station from the HLR. The subscriber information is downloaded to the VLR of the serving MSC. The serving MSC then uses the subscriber information to perform any required authentication tests. Upon satisfying the authentication tests, the MSC provides the services defined by the subscriber data to the mobile station.

Figure 2 illustrates the conventional telecommunications approach in an ANSI41 system for establishing a call between a first mobile station in an originating MSC coverage area and a second mobile station in a serving MSC coverage area. In step a, the originating MSC receives a call origination request and the dialed mobile station address bits (i.e. , the directory number of the second mobile station) from the first mobile station. The originating MSC sends a location request (LOCREQ) message to the HLR that stores the subscriber information for the second mobile station (step b). If the dialed mobile station address bits are assigned to a legitimate subscriber, the HLR sends a routing request (ROUTREQ) message to the VLR where the second mobile station is currently registered (step c). The VLR then forwards the routing request message to the serving MSC (step d). In response to the routing request message, the MSC requests the second mobile station's service information (i.e. , subscriber data) from the VLR (step e). If the second mobile station has not previously registered with the VLR and is therefore unknown to the VLR or if the information that is requested by the MSC is not available at the VLR, the VLR requests the information from the HLR (step f). In response, the HLR sends the requested information to the VLR (step g) which then routes the information to the serving MSC (step h). The serving MSC allocates a Temporary Local Directory Number (TLDN) for the second mobile station and returns this information to the VLR (step i) which then routes the information back to the HLR (step j).

The TLDN is a temporary routing number used to deliver calls to a serving system. The TLDN is de-allocated for a particular call at reception of a setup message from the originating system where the TLDN used as a called party address is mapped to the corresponding recipient identity (e.g., IMSI). The call setup technology is limited to ISUP or register signalling which is tightly coupled to the transport technology employed (e.g., SS7 or CAS).

When the TLDN is received by the HLR, it returns a location request response message to the originating MSC (step k). The originating MSC thereafter establishes a voice path to the serving MSC using existing interconnection protocols (e.g., SS7) and the routing information specified in the location request response message (step 1). While speech has been and will continue to be an important part of mobile communications, usage of mobile communication equipment for transmission of data rather than speech has become increasingly popular by consumers over the past decade. The possibility to send and receive electronic mail and to use a web browser to obtain world-wide-web access is frequently discussed as services that will be more and more used in wireless communication systems. As such, future communication systems will likely comprise a combination of telecommunication and data communication networks through which a call can be routed. As a result, it will be necessary to adapt existing telephony addressing techniques in order to provide a competitive edge for the telecommunication operators/service providers in the data communication industry that use IP-based or other data communication-based addressing schemes. There exists a need for a system and method for adapting the addressing schemes of conventional telecommunications systems so as to facilitate call establishment in environments comprising a combination of telecommunication and data communication networks.

SUMMARY

The present invention seeks to overcome the above-identified deficiencies in the art by providing a multi-protocol addressing scheme that allows for full interoperability between networks in a heterogeneous environment. According to exemplary embodiments of the present invention, a system and method is provided for statically or dynamically assigning to a user requesting access a virtual number parameter. The virtual number parameter is a generic routing address that provides all possible routable addresses (e.g., IP, ATM, X.25, user@realm, E.164, etc.) compatible to the routing technology supported by the system serving the particular user. Through the use of this virtual number parameter, call setup between heterogeneous and incompatible networks is facilitated.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and features of the present invention will be more apparent from the following description of the preferred embodiments with reference to the accompanying drawings, wherein:

Figure 1 illustrates a conventional wireless GSM telecommunication network; Figure 2 illustrates the conventional telecommunications approach for establishing a call between a first mobile station in an originating MSC coverage area and a second mobile station in a serving MSC coverage area;

Figure 3 illustrates an exemplary heterogeneous environment into which the addressing technique of the present invention may be employed; Figure 4 illustrates the use of the virtual number parameter of the present invention in an exemplary transaction in which a connection is established between an originating system (e.g., an Internet service provider) and a mobile station roaming in a visited system (e.g., a PLMN) wherein the originating system and the home system have different protocol capabilities;

Figure 5A illustrates the redirect method for establishing a connection between networks having different protocol capabilities;

Figure 5B illustrates the proxy method for establishing a connection between networks having different protocol capabilities; Figure 6 illustrates the use of the virtual number parameter of the present invention in a second exemplary transaction in which a connection is established between an originating system (e.g. , an Internet service provider (ISP)) and a mobile station roaming in a visited system (e.g., a PLMN) wherein the originating system and the home system have matching protocol capabilities; and Figure 7 illustrates an exemplary call forwarding transaction using the VNP address of the present invention.

DETAILED DESCRIPTION

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular circuits, circuit components, techniques, etc. in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, devices, and circuits are omitted so as not to obscure the description of the present invention.

As set forth above, future communication systems will provide the ability to route information through systems comprising both telecommunication networks (e.g., SS7) and data communication networks (e.g., the Internet). The current addressing mechanism used in telecommunication networks is tightly coupled to the transport technology utilized, for example SS7, which uses E.164, E.212, SS7 point codes, or other types of addressing. As a result, the current addressing mechanism is incapable of handling the various transport-independent schemes that will exist in future communication systems (e.g. , systems containing both data communication and telecommunication networks). The present invention provides a system and method for establishing a connection in a heterogeneous environment (i.e. , an environment comprising both telecommunication networks and data communication networks). According to exemplary embodiments of the present invention, a generic routing address that handles multi-protocol routing mechanisms, called a virtual number parameter (VNP), is employed. The VNP provides the necessary routing mechanisms for allowing an originating system to select one routing address from the VNP and one compatible call setup protocol from the capabilities of the serving system in order to set up and route the call. In those situations where the VNP is not supported, the system will fall back to existing solutions (e.g. , TLDN).

Figure 3 illustrates an exemplary heterogeneous environment into which the virtual number parameter of the present invention may be employed. As illustrated, the exemplary heterogeneous environment comprises an IP-based serving network 300, a SS7-based originating network 310 and a home network 320 which could be, for example, an IP-based network, a SS7-based network, etc. As one skilled in the art will appreciate, a mobile station's home network is that network containing the HLR that stores the particular mobile station's subscriber data and location information. For the sake of simplicity, it is assumed that each of the networks is similarly formed (i.e. , each network comprises a plurality of base transceiver stations and base station controllers, a mobile switching center, a visitor location register, a home location register, etc.). It will be further appreciated that in such systems some type of cooperating agreement should exist between the operators of all the heterogeneous networks. The serving system, the home system and the originating system can be part of any network using any agreed upon transport/routing/control technology. Therefore, in such heterogeneous environments, a call can originate from a data communications network to a telecommunications network or vice versa, from a first data communications network to a second data communications network or from a first telecommunications network to a second telecommunications network.

The VNP addressing technique of the present invention will now be described with reference to the exemplary heterogenous environment illustrated in Figure 3. In Figure 3 , it is assumed that mobile station MS has roamed out of its home coverage area (i.e. out of the area covered by the home system 320) and into the coverage area of a data communications network (e.g., an IP-based network 300). When the mobile station roams into or is activated in the coverage area of the serving network 300 (i.e. , the IP-based network), the mobile station registers with the serving network 300 by sending a registration request that comprises the mobile station's identifier, e.g., IMSI. According to exemplary embodiments of the present invention, the serving network 300, in response to the registration request, allocates a virtual number parameter (VNP) to the subscriber and provides that parameter in the registration message towards the home system 320. According to this example where the serving network 300 is an IP-based network, the VNP includes an IP address in addition to any other type of addresses that is compatible to the routing technology supported by the serving system. In other words, the VNP of the present invention uniquely identifies alias addresses for a specific subscriber or addressable network entity (e.g., terminals, etc.). The VNP comprises such information as the address type, address length and the address itself and is added to existing network transactions, such as database queries, call delivery, roaming, redirection, etc. The registration message also includes the mobile station's IMSI and information indicating the protocol capabilities of the serving network 300 (e.g. , SIP, H.323, HTTP, etc.) and optionally a timer for setting a time period in which the VNP is valid. It will be appreciated that without the timer, the VNP could, for example, be allocated as long as the mobile is registered. Upon receipt of the registration message from the serving network 300, the home system 320 stores the VNP, acknowledges the registration message and starts a timer for the supervision for the VNP. The timer can be either provided by the serving system that owns the VNP, as described above, or generated by the home system. The serving system may also request the home system to allocate a VNP on its behalf. In those situations where the home system generates the timer for the supervision of the VNP, the serving system is informed when the timer expires. The serving system can then request that the supervision of the VNP continue or that the VNP for that specific user be discarded. Upon de-registration and/or inactivity (i.e., expiration of the timer), the home system removes the VNP from the user's database and discontinues supervision.

In an alternative embodiment, the terminal used by the user may also have the capability of providing the routable addresses in a VNP attribute. In such a situation, the content of the VNP attribute may be negotiated with the serving system. If the serving system would not support any of the possible routable addresses, it may provide connectivity by tunneling requests and pay load from and to the terminal.

Figure 4 illustrates the use of the virtual number parameter of the present invention in an exemplary transaction in which a connection is established between an originating system (e.g., an Internet service provider) and a mobile station roaming in a visited system (e.g., a PLMN) wherein the originating system and the home system have different protocol capabilities. A user from the originating system (i.e., the ISP in this example) attempts to locate a registered subscriber currently roaming in the PLMN (i.e., the serving/visited system). Since, according to this embodiment of the present invention, it is assumed that the home system cannot communicate directly with the originating data communications network, a PLMN gateway is employed. The location request includes, inter alia, the called party's address and the protocol capabilities of the originating system and is routed from the serving system to the PLMN gateway. The gateway system analyzes the request and the called party's address which could be an Internet-type of address. The gateway performs or orders address mapping to, for example, an E.164 address type. The gateway system then analyzes the new address received from the mapping function (e.g., DNS) and formulates a location request to the corresponding home system in order to obtain a VNP. The request includes additional call information (e.g., call type, bearer capability, etc.) and the originating network's protocol capabilities.

The home system analyzes the request and, in those situations where a valid VNP is stored in the home system's HLR for the subscriber, the home system routes the VNP to the originating system after successfully matching the serving system's protocol capabilities to the originating system's protocol capabilities.

If a VNP is not available in the HLR for that subscriber, the home system then initiates a request to the serving system to connect the subscriber. The request also includes the call information and capabilities received by the originating system. The serving system locates the subscriber, assigns a traffic channel if necessary and reserves required data handling resources (e.g., interworking function, traffic terminals, etc.).

At this point, the serving system may choose between different packet call routing options based on the serving and originating systems' capabilities. The following options are possible:

1) Return a VNP, including, for example, an IP address, to the originating system. Within the originating system, the PLMN gateway forwards the received address to the ISP network. The ISP network then sets up a new session towards the address provided by the VNP.

2) Return an E.164 type of routing digits (e.g. , a temporary local directory number (TLDN)) to the originating system. The routing digits are then used by the PLMN gateway within the originating system to set up a connection towards the serving system. This option may be selected in those situations where the system cannot support VNP. If the IP address previously allocated to the subscriber has expired, a new IP address will be included in the routing request return result as a VNP. The home system stores the new routing IP address and includes it in the response of the location request back to the originating system. If the serving system's protocol capabilities do not match with the originating system's capabilities, the home system may select another gateway that is capable of handling the protocol mapping between the serving system and the originating system so that a successful connection setup results. The home system may choose to include the address of the gateway in the response to the originating system (Redirect method) or it may use a proxy server to set up the connection through the gateway towards the serving system (Proxy method) ^and inform the originating system of the gateway address and the connection status information (e.g., the connection method and the result). The originating system then sets up the connection either through the gateway towards the serving system or it completes the connection towards the gateway where the connection from the gateway towards the serving system has previously been established. If any failure occurs (e.g. , proxy failure, etc.) when connecting the gateway to the serving system, the originating system is notified of the appropriate failure information.

Figures 5 A and 5B illustrate the above-described redirect and proxy methods. In Figure 5A, a user in the originating network sends a location request, which includes, inter alia, the protocol capabilities of the originating network to the home network in an attempt to locate a registered subscriber (step 501). In response, the home network sends a request to the serving network (step 502) which locates the registered subscriber and assigns the appropriate resources (it should be noted that for this example and the example set forth below with respect to Figure 5B, it is assumed that the home system does not contain a valid VNP for the subscriber). The serving network sends a VNP to the home network (step 503) along with the protocol capabilities of the serving network. Upon determining that the serving network and the originating network have different protocol capabilities, the home network chooses a gateway that is capable of handling the protocol mapping. The home network includes the address of the gateway in a message to the originating network (step 504). The originating network then sends a connection request to the gateway (step 505) which establishes a connection with the serving network (step 506). Thereafter, the user and the registered subscriber communicate via the gateway (steps 507a and 507b).

Figure 5B illustrates the proxy method for establishing a connection between networks having different protocol capabilities. In step 551, a user in the originating network sends a location request, which includes, inter alia, the protocol capabilities of the originating network to the home network in an attempt to locate a registered subscriber. In response, the home network sends a request to the serving network (step 552) which locates the registered subscriber and assigns the appropriate resources. The serving network sends a VNP to the home network (step 553) along with the protocol capabilities of the serving network. Upon determining that the serving network and the originating network have different protocol capabilities, the home network chooses a gateway that is capable of handling the protocol mapping. The home network, through the use of a proxy server, sets up a connection with the serving network through the gateway (steps 554-556). In step 557, the home network then notifies the originating network of the gateway address and connection status information (e.g. , the connection method and result). The originating system then completes the connection with the gateway (steps 558 and 559).

Figure 6 illustrates the use of the virtual number parameter of the present invention in a second exemplary transaction in which a connection is established between an originating system (e.g. , an Internet service provider (ISP)) and a mobile station roaming in a visited system (e.g. , a PLMN) wherein the originating system and the home system have matching protocol capabilities. Since the originating system and home system have matching protocol capabilities, the originating network of Figure 6 does not include a PLMN gateway. Similar to the exemplary transaction illustrated in Figure 4, a user from the Internet attempts to locate a registered subscriber currently roaming in the PLMN. Since, as set forth above, the home system is capable of communicating directly with an ISP or other data communications network, no gateway is necessary. As such, the ISP sends a location request, which includes, inter alia, the called party's address and the protocol capabilities of the originating system, directly to the home system.

In those situations where the HLR of the home system contains a valid VNP for the subscriber, the VNP is routed from the HLR to the originating system. When the HLR does not contain a valid VNP for the subscriber, the home system initiates a request to the serving system to connect the subscriber. The serving system pages the registered subscriber, assigns a traffic channel if necessary and reserves the required data handling resources (e.g. , interworking function).

If the IP address previously allocated to the registered subscriber has expired, a new IP address is included in the routing request return result from the serving system as a VNP. As set forth above, the routing request return result may also include a timer for supervising the use of the VNP. The home system stores the new IP address and includes it in the response to the location request back to the originating system (i.e. the ISP). The serving system's Internet protocol capabilities are also included in the response to the originating system. In those situations where the protocol capabilities of the originating and serving systems match, the call is then set up directly from the ISP to the serving system using the IP address supplied by the serving system. If the serving system's protocol capabilities are different than those of the originating system, then the home system may choose to use the redirect or proxy method described above to set up the call. Figure 7 illustrates an exemplary call forwarding transaction using the VNP of the present invention. Similar to the exemplary transaction described above with respect to Figure 4, a call is established between an Internet service provider and a registered subscriber in a PLMN. It is assumed herein that the serving system returns, in response to a request from the home system, a E.164 format TLDN back to the gateway. The originating system then sets up the connection using the TLDN provided by the serving system. If after a predetermined timeout period the registered subscriber has not responded, the serving system sends a redirection message to the originating system indicating that the registered subscriber has not replied. In those situations where the redirection message comprises a redirection address (i.e., the VNP), the originating system sets up the connection using that address. When, however, the redirection message does not contain a redirection address, the originating system requests one from the home system. The home system sends the VNP to the originating system which then sets up a connection to the address provided by the VNP. As evident from the above-described embodiments, modifications to existing telecommunications network entities and the related interfaces are needed. It will be appreciated that conventional telecommunications protocols could be modified to support the above-described functionality or new protocols could be developed. The present invention provides the following enhancements to conventional telecommunications networks:

• Telecommunications databases and network entities able to support multi-protocol addressing schemes (e.g. , IP, user@realm, ATM, X.25).

• The ability to provide all available alias addresses (E.164, IP address, name etc.) for subscriber identification, authentication, translation and routing for a specific operation.

• The ability to identify the preferred addressing type used per operation when communicating with another network entity.

• The overall network is informed about each node's address handling capabilities using one or more of the following procedures: broadcast method or cooperating agreement administered manually in each network entity or by providing the address handling capabilities in every exchanged operation (e.g. , transaction capabilities parameter in ANSI41 etc.).

• In SS7 networks, messages carrying digits for the purpose of identification, routing, redirection, etc., will include other alternate addresses in a VNP optional parameter.

• The life cycle of the VNP assigned to the registered user is time supervised by the serving system and/or the home system.

• The home system stores VNP's and is capable of locating users, routing incoming calls, transferring and forwarding calls from any type of communication system.

• For terminating accesses, the home system indicates a call type, such as packet data calls of different types (SIP, H.323, etc.).

• The ability in the SCCP to support a new global translation type to provide virtual number address translation to a destination address. • The VNP allows for locating a user and routing calls regardless of the routing technology used by the network entities.

• The content of the VNP attribute is flexible and may be negotiated with the serving system.

The present invention provides, through the use of a virtual number parameter, the ability to dynamically or statically assign a user requesting access in an environment having a combination of telecommunication and data communication networks all possible routable addresses for establishing a connection. The VNP provides all possible routing mechanisms that will allow an originating system to select one routing address from the VNP and one compatible call setup protocol from the capabilities of the serving system in order to set up and route the call. The VNP may be allocated by the home system or serving system during registration of a subscriber or by a gateway or other system during call routing. The VNP of the present invention may also be assigned by a subscriber's own terminal.

The foregoing has described the principles, preferred embodiments and modes of operation of the present invention. However, the invention should not be construed as being limited to the particular embodiments discussed above. For example, while many of the exemplary embodiments set forth above indicate the use of a specific routing protocol, one skilled in the art will appreciate that the present invention is not so limited. In fact, the present invention is equally applicable to any routing protocol. Thus, the above-described embodiments should be regarded as illustrative rather than restrictive, and it should be appreciated that variations may be made in those embodiments by workers skilled in the art without departing from the scope of the present invention as defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method for providing inter-operability between heterogenous and incompatible networks, said method comprising the steps of: assigning a virtual number parameter; and establishing a connection between said heterogeneous and incompatible networks using said virtual number parameter, wherein said virtual number parameter is a generic routing address.

2. The method of claim 1 wherein said virtual number parameter comprises multi-protocol addressing information.

3. The method of claim 1 wherein said virtual number parameter is assigned during a registration procedure.

4. The method of claim 1 wherein said virtual number parameter is assigned during call routing.

5. The method of claim 1 wherein said virtual number parameter is assigned by a serving network.

6. The method of claim 1 wherein said virtual number parameter is assigned by a home network.

7. The method of claim 1 wherein said virtual number parameter is assigned by a gateway.

8. The method of claim 1 wherein said virtual number parameter is assigned by a user's terminal.

9. The method of claim 1 further comprising the steps of: transmitting a location request from a first user in an originating system to a home system of a second user, said second user located in a coverage area of a serving system; and transmitting a response comprising said assigned virtual number parameter from said home system to said originating system, wherein a connection is established between said originating system and said serving system using said virtual number parameter.

10. The method of claim 9 wherein said virtual number parameter is a multiprotocol address assigned by said serving system.

11. The method of claim 9 wherein said virtual number parameter comprises at least one address that matches routing/transport capabilities of said serving system.

12. The method of claim 9 wherein said location request comprises an indication of protocol capabilities of said originating system.

13. The method of claim 12 further comprising the step of: determining, in response to said location request, whether a valid virtual number parameter for said second user is stored at said home network.

14. The method of claim 13 further comprising the steps of: transmitting, when a valid virtual number parameter is not present at said home network, a request for a routing address from said home system to said serving system; transmitting, in response to said request for a routing address, the virtual number parameter and an indication of the protocol capabilities of said serving system to said home system; and determining whether the protocol capabilities of said originating system and said serving system match, wherein said virtual number parameter is transmitted to said originating system when the protocol capabilities match and said originating system establishes said connection using an appropriate protocol and said virtual number parameter.

15. The method of claim 14 further comprising the step of: performing a redirect procedure when said protocol capabilities do not match.

16. The method of claim 14 further comprising the step of: performing a proxy procedure when said protocol capabilities do not match.

17. The method of claim 13 further comprising the step of: determining, when a valid virtual number parameter is determined to exist, whether the protocol capabilities of said originating system and said serving system match, wherein said virtual number parameter is transmitted to said originating system when the protocol capabilities match and said originating system establishes said connection using an appropriate protocol and said virtual number parameter.

18. The method of claim 17 further comprising the step of: performing a redirect procedure when said protocol capabilities do not match.

19. The method of claim 17 further comprising the step of: performing a proxy procedure when said protocol capabilities do not match.

20. The method claim 1 wherein the assignment of said virtual number parameter is supervised through the use of a timer.

21. A system for providing inter-operability between heterogenous and incompatible networks, said system comprising: means for assigning a virtual number parameter; and means for establishing a connection between said heterogeneous and incompatible networks using said virtual number parameter, wherein said virtual number parameter is a generic routing address.

22. The system of claim 21 wherein said virtual number parameter comprises multi-protocol addressing information.

23. The system of claim 21 wherein said virtual number parameter is assigned during a registration procedure.

24. The system of claim 21 wherein said virtual number parameter is assigned during call routing.

25. The system of claim 21 wherein said means for assigning is a serving network.

26. The system of claim 21 wherein said means for assigning is a home network.

27. The system of claim 21 wherein said means for assigning is a gateway.

28. The system of claim 21 wherein said means for assigning is a user's terminal.

29. The system of claim 21 further comprising: means for transmitting a location request from a first user in an originating system to a home system of a second user, said second user located in a coverage area of a serving system; and means for transmitting a response comprising said assigned virtual number parameter from said home system to said originating system, wherein a connection is established between said originating system and said serving system using said virtual number parameter.

30. The system of claim 29 wherein said virtual number parameter is a multi-protocol address assigned by said serving system.

31. The system of claim 29 wherein said virtual number parameter comprises at least one address that matches routing/transport capabilities of said serving system.

32. The system of claim 29 wherein said location request comprises an indication of protocol capabilities of said originating system.

33. The system of claim 32 further comprising: means for determining, in response to said location request, whether a valid virtual number parameter for said second user is stored at said home network.

34. The system of claim 33 further comprising: means for transmitting, when a valid virtual number parameter is not present at said home network, a request for a routing address from said home system to said serving system; means for transmitting, in response to said request for a routing address, the virtual number parameter and an indication of the protocol capabilities of said serving system to said home system; and means for determining whether the protocol capabilities of said originating system and said serving system match, wherein said virtual number parameter is transmitted to said originating system when the protocol capabilities match and said originating system establishes said connection using an appropriate protocol and said virtual number parameter.

35. The system of claim 34 wherein said home system performs a redirect procedure when said protocol capabilities do not match.

36. The system of claim 34 wherein said home system performs a proxy procedure when said protocol capabilities do not match.

37. The system of claim 33 further comprising the steps of: means for determining, when a valid virtual number parameter is determined to exist, whether the protocol capabilities of said originating system and said serving system match, wherein said virtual number parameter is transmitted to said originating system when the protocol capabilities match and said originating system establishes said connection using an appropriate protocol and said virtual number parameter.

38. The system of claim 37 wherein said home system performs a redirect procedure when said protocol capabilities do not match.

39. The system of claim 37 wherein said home system performs a proxy procedure when said protocol capabilities do not match.

40. The system of claim 29 wherein said means for transmitting a location request is a gateway.

41. The system of claim 21 further comprising a timer for supervising said virtual number parameter.