JP2002543677A - Virtual numbering plan for interworking between heterogeneous networks - Google Patents

Abstract

(57) Abstract The present invention provides a multi-protocol addressing method that enables complete interoperation between networks in a heterogeneous environment. According to exemplary embodiments, systems and methods are statically or dynamically assigned to users requesting access. The virtual number parameter specifies all routable addresses (eg, IP, ATM, X.25, user @ realm, E.164, etc.) that are compatible with the routing technology supported by the system supporting the particular user. provide. The use of this virtual number parameter facilitates call setup between different networks.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION The present invention relates generally to communication systems, and more particularly to telecommunications (telec).
A method and structure for establishing a connection in a cellular environment that includes an ommunication network and a data communication network.

[0002] Global System for Mobile (GSM) communication is a communication standard in Europe and provides uniformity so that users can access the communication system through any GSM system with minimal equipment compatibility issues. Describes the intended Public Land Mobile Network (PLMN). Thus, the PLMN telephone communication system has provided the mobile subscriber with the ability to move freely within the GSM system and utilize the mobile services provided therein.

FIG. 1 shows a typical conventional wireless GSM telephony network. Conventional wireless G
An SM telephone communication system generally includes a base transceiver station (BTS) and a base station controller (BTS).
BCS), Mobile Switching Center (MSC) with Visitor Location Register (VLR)
) And a home location register (HLR) having an authentication center (AuCs).
)including.

[0004] Each BTS provides communication to one or more mobile stations (MS) located in respective cells or zones of the wireless network. The BSC controls the operation of one or more BTSs. The BSC is intended for the intended destination (eg, the public switched telephone network (PSTN)
)) Interconnected with the MSC routing information. Each MSC has an HLR
And VLR. The HLR stores location information and subscriber data that define the services allowed for each mobile station. The VLR stores subscriber data for the mobile station currently located in the service area of the corresponding MSC. Additional information regarding conventional wireless telephony networks is provided in US Pat. No. 5,862,481 to Kulkarni et al. And Joensuu, all of which are expressly incorporated herein by reference.
No. 5,867,788 to U.S. Pat.

In conventional telephony, when a mobile station moves to the coverage area of a new MSC or is powered on, the mobile station first attempts to register with the serving MSC. The registration process is completed by the mobile station transmitting an associated identifier (for example, an International Mobile Subscriber Identity (IMSI) number) to the MSC that provides the service. The IMSI is mapped by the system to the mobile station's MSISDN, as known to those skilled in the art.

The serving MSC uses this information to inform the new location of the mobile station and to store the subscriber information for the requested mobile station in order to retrieve the subscriber information for that mobile station. Communicates with The subscriber information is downloaded to the VLR of the serving MSC. The serving MSC then uses the subscriber information to perform any necessary authentication tests. If you meet the certification test,
The MSC provides services defined by the subscriber data to the mobile station.

FIG. 2 illustrates a first mobile station and a serving MSC in the original MSC coverage area.
41 for establishing a call with a second mobile station in a coverage area of
FIG. 2 is a diagram showing a conventional telephone communication method in the system. In step a, the original MSC receives the call request and the address bits of the dialed mobile station (ie, the directory number of the second mobile station) from the first mobile station. The original MSC sends a location request message (LOCREQ) 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 will send a routing request (ROUTREQ
) Sending a message to the VLR with which the second mobile station is currently registered (step c)
.

[0008] The VLR then forwards the routing request message to the serving MSC (step d). In response to the routing request message, the MSC requests service information (ie, subscriber data) of the second mobile station from the VLR (step e). If the second mobile station is not pre-registered with the VLR and is therefore not known to the VLR or the information requested by the MSC is not available in 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 routes the information to the serving MSC (step h). The serving MSC assigns a temporary local directory number (TLDN) to the second mobile station and returns this information to the VLR (step i). The VLR routes this information to the HLR (step j).

[0009] The TLDN is a temporary routing number used to provide a call to a serving system. The TLDN is de-assigned to a particular call upon receipt of a configuration message from the calling system that maps to the corresponding recipient identifier (eg, IMSI) used as the called party address. Call setup techniques are limited to ISUP or registration signaling that is tightly coupled to the transport technology used (eg, SS7 or CAS).

When the TLDN is received by the HLR, the HLR returns a location request response message to the calling MSC (step K). The calling MSC then establishes a voice path to the serving MSC using the existing interconnect protocol (eg, SS7) and the routing information specified in the location request response message (step l).
.

Although voice communications have been and will continue to be an important part of mobile communications, the use of mobile communication devices for data transmission rather than voice over the past decade has become increasingly popular with consumers. Have gained.

[0012] The possibility of using a web browser to send and receive e-mail and provide World Wide Web access is often considered as a service that will be increasingly used in wireless communication systems. Thus, future communication systems will include a combination of voice and data communication networks that can be routed through them. As a result, existing telephone numbering plans are needed to provide a competitive edge for telecommunication operators or service providers in the data communications industry using IP-based or other data-based addressing methods.

[0013] There is a need for systems and methods that adapt to conventional telephone communication system addressing schemes to facilitate call establishment in environments that include a combination of telephone and data communication networks.

SUMMARY OF THE INVENTION The present invention seeks to overcome the above shortcomings by providing a multi-protocol addressing scheme that provides complete interoperability between networks in heterogeneous environments. According to an exemplary embodiment of the present invention, a system and method are provided for statically or dynamically assigning a user who has requested access to a virtual number parameter. The virtual number parameter specifies all possible routable addresses (e.g., IP, ATM, X.25, user @ realm, E) that are compatible with the routing technology supported by the system serving the particular user. .164, etc.).
Through the use of this virtual number parameter, call setup between heterogeneous and incompatible networks is facilitated.

The above objects and features of the present invention will become more apparent from the following description of preferred embodiments with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION In the following description, for purposes of explanation and not limitation, specific circuits, circuit components,
Methods and the like are described to provide a thorough understanding of the present invention. However, it will be readily 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 mentioned above, future communication systems will transfer information over a telephone communication network (eg, SS
7) and the ability to route through systems that have both a data communication network (eg, the Internet). The addressing mechanism currently used in telephony networks is based on the transport technology used, e.g. 164; 2
12, is tightly coupled to SS7 using SS7 point codes or other forms of addressing. As a result, current addressing schemes cannot handle a variety of carrier technology independent approaches that will exist in future communication systems (eg, systems that include both data and telephony networks). The present invention provides systems and methods for establishing a connection in a heterogeneous environment (ie, an environment having both a telephony network and a data communication network).

According to an exemplary embodiment of the present invention, a multi-protocol routing mechanism called a virtual number parameter (VNP) is used. The VNP provides the calling system with one routing address from the VNP for call setup and routing.
One compatible call setup protocol can be selected from the capabilities of the service providing system. If VNP is not supported, the system falls back to an existing solution (eg, TLDN).

FIG. 3 illustrates a typical heterogeneous environment in which the virtual number parameter of the present invention can be used. As shown, a typical heterogeneous environment includes an IP-based serving network 300, an SS7-based calling network 310 and,
And a home network 320 which may be a network based on SS7, etc. Those skilled in the art will appreciate that a mobile station's home network includes an HLR that stores subscriber data and location information for a particular mobile station. For simplicity, it is assumed that each network is similarly configured (ie, each network has multiple base transceiver stations and base station controllers, mobile switching controllers, visitor location registers, home location registers, etc.).

In such a system, there should be several types of cooperation agreements between operators of all heterogeneous networks. The serving system, home system and calling system can be part of any network that uses agreed transport / routing / control methods. Thus, in such a heterogeneous environment, a call may be made from a data communication network to a telephone communication network or vice versa from a first data communication network to a second data communication network or from a first telephone communication network to a second data communication network. To the telephone communication network.

Hereinafter, the VNP addressing method of the present invention will be described with reference to the typical heterogeneous environment shown in FIG. In FIG. 3, the mobile station MS has moved out of its home coverage area (ie, has gone out of the area covered by the home system 320) and has a coverage area of a data communication network (eg, IP-based network 300). Assume that you have entered The mobile station is serving network 3
00 (ie, an IP based network) coverage area,
When powered on in the area, the mobile station registers with the serving network 300 by sending a registration request that includes a mobile station identifier, eg, IMSI.

According to an exemplary embodiment of the present invention, in response to a registration request, serving network 300 assigns a virtual number parameter (VNP) to a subscriber and provides that parameter in a registration message to home system 320. I do. According to the present embodiment, the service providing network 300 is a network based on IP,
P includes the IP address in addition to the IP address in addition to any other type of address that is compatible with the routing methods supported by the service providing system.

In other words, the VNP of the present invention uniquely identifies an alias address for a particular subscriber or addressable network entity (eg, a terminal). The VNP includes information such as an address type, an address book, and an address itself. The VNP includes the address book itself, and the VNP adds an existing network transaction. Also, database queries, database queries, call delivery,
It is added to existing network transactions such as roaming and redirection. The registration message also includes information indicating the IMSI of the mobile station and the protocol capabilities of the serving network 300 (eg, SIP, H.323, HTTP, etc.) and, if necessary, a timer for setting the validity time of the VNP. It will be appreciated that without a timer, VNP may be valid as long as the mobile station is registered, for example.

Upon receiving the registration message from the service providing network 300, the home system 320 stores the VNP, acknowledges the registration message, and
Start a timer to monitor The timer may be provided by the service providing system having the VNP as described above, or may be generated by the home system. The service providing system may also request the home system to allocate a VNP for use in the service providing system. Thus, when the home system generates the VNP monitoring timer, the service providing system is notified when the timer expires. The service providing system can request whether to continue monitoring the VNP or discard the VNP for that particular user. Upon deregistration and / or inactivity (ie, the timer expires), the home system removes the VNP from the user's database and stops monitoring.

In an alternative embodiment, the terminal used by the user may also have the ability to provide a routable address in the VNP attribute. In such a situation, the contents of the VNP attribute are negotiated with the service providing system. If the service providing system does not support any of the possible routing addresses, it is possible to provide connectivity by tunneling requests and payloads from / to the terminal.

FIG. 4 illustrates a book in a typical process in which a connection is established between a calling system (eg, an Internet service provider) having different protocol capabilities and a mobile station traveling to a target system (eg, a PLMN). 4 illustrates the use of a virtual number parameter according to the invention. A user from the calling system (the ISP in this embodiment) attempts to locate a registered subscriber currently moving to the PLMN (eg, a serving / destination system). According to this embodiment of the invention, a PLMN gateway is used because it assumes that the home system cannot communicate directly with the calling data communication network. The locate request includes the called party address and the protocol capabilities of the calling system, among others, and is routed from the serving system to the PLNM gateway.

The gateway system parses the request and the called party address, which can be an Internet-style address. The gateway is, for example, E.I. Perform or instruct address mapping to 164 format. Then, the gateway system analyzes the new address received from the mapping function (for example, DNS), and formulates a location request to the corresponding home system to obtain the VNP. The request includes additional call information (eg, call type, bearer capabilities, etc.) and the protocol capabilities of the calling network.

The home system analyzes the request and, if a valid VNP for the subscriber is stored in the home system's HLR, successfully matches the protocol capabilities of the serving system to those of the calling system. After that, the VNP is routed to the calling system.

If no VNP is available for the subscriber in the HLR, the home system initiates a request to the serving system to connect to the subscriber. The request also includes the call information and capabilities received by the calling system. The service delivery system locates the subscriber, allocates traffic channels if necessary,
Secure required data processing resources (eg, interworking functions, traffic terminals, etc.).

At this point, the serving system can select different packet call routing options based on the capabilities of the serving system and the calling system. The following options are possible:

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

2) E. A 164 format routing digit (eg, a temporary local directory number (TLDN)) is returned to the calling system. The routing digits are then used by the PLMN gateway inside the calling system to set up a connection to the serving system. This option may be selected if the system cannot support VNP.

If the IP address previously assigned to the subscriber has expired, the new IP address will be included in the routing request return result as VN. The home system stores the new routing IP address and returns it to the calling system in a response to the location request. If the protocol capabilities of the serving system do not match the capabilities of the calling system, the home system must provide another protocol mapping process between the serving system and the calling system to obtain a successful connection setup result. You can select a gateway. The home system can include the gateway address in the response to the calling system (redirect method) or use a proxy server to set up a connection to the service providing system through the gateway (proxy method). , And notifies the calling system of the gateway address and connection state information (for example, the connection method and the result thereof). The calling system sets up a connection through a gateway to the service providing system, or completes a connection to a gateway in which a connection to the service providing system has been established in advance. If any failure occurs when connecting the gateway to the service providing system (for example, a proxy failure), appropriate failure information is notified to the calling system.

FIGS. 5A and 5B illustrate the redirection and proxy methods described above. In FIG. 5A, during a location attempt of a registered subscriber, a user of the calling network sends a location request to the home network, particularly including the protocol capabilities of the calling network (step 501). In response, the home network locates the registered subscriber and sends a request to the serving network that allocates the appropriate resources (step 502) (in the present description and in the following description of FIG. 5B, the home network). The system assumes that it does not contain a valid VNP for that subscriber).

The service providing system sends the VNP to the home network together with the protocol capabilities of the service providing system (step 503). If the serving network and the calling network are found to have different protocol capabilities, the home network selects a gateway capable of protocol mapping. The home network includes the address of the gateway in the message to the calling network (step 504). Then, the calling network sends a connection request to the gateway (step 505), and the gateway establishes a connection with the service providing network (step 506). Thereafter, the user and the registered subscriber communicate via the gateway (steps 507a and 507b).

FIG. 5B illustrates a proxy method for establishing a connection between networks having different protocol capabilities. At step 551, a user at the calling network sends a location request to the home network during the location attempt of the registered subscriber, specifically including the protocol capabilities of the calling network. In response, the home network sends a request to the serving network to locate the registered subscriber and allocate the appropriate resources (step 552). The serving network sends the VNP with its protocol capabilities to the home network (step 553).

If it is found that the serving network and the calling network have different protocol capabilities, the home network selects a gateway capable of protocol mapping. The home network establishes a connection with the service providing network via the gateway through the use of a proxy server (steps 554-556). Then, in step 557, the home network notifies the calling side network of the gateway address and the connection state information (for example, connection method and result). Then, the calling system completes the connection with the gateway (steps 558 and 559).

FIG. 6 shows a second example where a connection is established between a calling system (eg, an Internet service provider) with matching protocol capabilities and a mobile station traveling to a target system (eg, a PLMN). Fig. 4 illustrates the use of the virtual number parameter according to the present invention in a simple process. The calling network of FIG. 6 does not include a PLMN gateway because the calling system and the home system have matching protocol capabilities.

As with the typical process shown in FIG. 4, users from the Internet
Attempt to locate the registered subscriber moving to N.

As mentioned above, a gateway is not required since the home system can communicate directly with an ISP or other data communication network. Thus, the ISP sends a location request directly including the called party address and the protocol capabilities of the calling system directly to the home system.

If the home system's HLR contains a valid VNP for the subscriber, the VNP is routed from the HLR to the calling system. If the HLR does not contain a valid VNP for the subscriber, the home system initiates a request to the serving system to connect to the subscriber. The service provider calls the registered subscriber, allocates traffic channels if necessary, and secures the necessary data processing resources (eg, interworking functions).

If the IP address previously assigned to the registered subscriber has expired, the new IP address is included in the routing request response result from the service providing system as VNP. As described above, the routing request response result is also V
It may further include a timer used for monitoring the NP. The home system stores the new IP address and includes it in the locate request response sent back to the calling system (ie, the ISP). The response to the calling system may also include the Internet Protocol capabilities of the service providing system. If the protocol capabilities of the calling party and the serving system match, the call is set up directly from the ISP to the serving system using the IP address provided by the serving system.

If the protocol capabilities of the serving system are different from the protocol capabilities of the calling system, the home system can select the redirect or proxy method described above to set up the call. .

FIG. 7 shows a typical call forwarding process using the VNP of the present invention. Similar to the exemplary process described above with respect to FIG. 4, a call is established between an Internet service provider and a registered subscriber in the PLMN. Here, the service providing system responds to the request from the home system and transmits the E.E. It is assumed that the 164 format TLDN is returned to the gateway. Then, the calling system sets up a connection using the TLDN supplied from the service providing system. If the registered subscriber does not respond after a predetermined timeout period, the service providing system sends a redirection message to the calling system indicating that the registered subscriber does not respond. If the redirection message includes a redirection address (ie, VNP), the calling system uses that address to set up a connection. However, if the redirection message does not include a redirection address, the calling system requests a redirection address from the home system. The home system sends a VNP to the calling system, which sets up a connection to the address provided by the VNP.

As is apparent from the above embodiments, modifications to existing telephony network entities and associated interfaces are needed. It will be appreciated that conventional telephony protocols can be modified to support the features described above, or new protocols can be developed. The present invention provides the following enhancements to a conventional telephone communication network.

A plurality of addressing methods (eg, IP, user area, ATM, X25)
Telephony database and network entity that can support. Ability to provide all available proxy addresses (E.164, IP address, name, etc.) for subscriber identification, authentication, translation and routing for specific operations.

The ability to specify a preferred addressing format to use for each operation when communicating with other network entities. Each one to the entire network, using one or more of broadcast methods or cooperation agreements managed by each network entity mutually, or provision of address processing capability (eg, parameter processing capability in ANSI 41) for each exchange operation. Notification of node address processing capability.

In SS7 networks, messages carrying digits for identification, routing, redirection, and other purposes include other alternative addresses in VNP option parameters. -The lifetime of the VNP assigned to the registered user is monitored by the service providing system and / or the home system.

The home system stores the VNP and has the ability to locate the user, route incoming calls, transmit and forward calls from any type of communication system. The home system indicates a different form of packet data call (SIP, H.323, etc.) to terminate the access.

The ability in SCCP to support a new global translation format to provide virtual number address translation for destination addresses. VNP that allows user location and call routing independent of the routing technology used at the network entity. -The content of the VNP attribute is flexible and can be negotiated with the service providing system.

Through the use of the virtual number parameter, it provides the ability to assign the user requesting access to an environment or other system that is either dynamically or statically during call routing. The VNP of the present invention may also be assigned by the 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 limited to the particular embodiments discussed above.
For example, while many of the exemplary embodiments described above show the use of a particular routing protocol, those skilled in the art will appreciate that the invention is not so limited. In fact, the invention is equally applicable to any routing protocol.

Therefore, the above embodiments are to be regarded as illustrative rather than restrictive, and without departing from the scope of the invention, which is defined in the following claims. It should be understood that various modifications can be made to these embodiments.

[Brief description of the drawings]

FIG. 1 illustrates a conventional wireless GSM telephone communication network.

FIG. 2 illustrates a conventional communication procedure for establishing a call between a first mobile station in a calling MSC coverage area and a second mobile station in a serving MSC coverage area. .

FIG. 3 illustrates a typical heterogeneous environment to which the addressing method of the present invention can be applied.

FIG. 4 illustrates the present invention in a typical transaction in which a connection is established between a calling system having different protocol capabilities (eg, an Internet service provider) and a mobile station roaming to a target system (eg, a PLMN). FIG. 7 is a diagram showing the use of the virtual number parameter of FIG.

FIG. 5A illustrates a redirect method for establishing a connection between networks having different protocol capabilities.

FIG. 5B illustrates a proxy method for establishing a connection between networks having different protocol capabilities.

FIG. 6 is a second exemplary transaction in which a connection is established between a calling system (eg, an Internet service provider) having different protocol capabilities and a mobile station roaming to a target system (eg, a PLMN). FIG. 5 illustrates the use of the virtual number parameter of the present invention in FIG.

FIG. 7 illustrates an exemplary call transfer transaction using the VNP address of the present invention.

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Claims (41)

[Claims] 1. A method for providing interoperability between heterogeneous and incompatible networks, comprising the steps of: allocating a virtual number parameter; and using the virtual number parameter between the heterogeneous and incompatible networks. Establishing a connection, wherein the virtual number parameter is a universal routing address. 2. The method of claim 1, wherein the virtual number parameter comprises addressing information for a plurality of protocols. 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 the virtual number parameter is assigned by a serving network. 6. The method of claim 1, wherein the virtual number parameter is assigned by a home network. 7. The method of claim 1, wherein the virtual number parameter is assigned by a gateway. 8. The method of claim 1, wherein the virtual number parameter is assigned by a user terminal. 9. transmitting a location confirmation request from a first user in a calling system to a home system of a second user located in a coverage area of a service providing system; and transmitting the call from the home system. Transmitting a response having the assigned virtual number parameter to a calling system, wherein a connection is established between the calling system and the service providing system using the virtual number parameter. The method of claim 1, wherein: 10. The method according to claim 9, wherein the virtual number parameter is a multi-protocol address assigned by the service providing system. 11. The method of claim 9, wherein the virtual number parameter comprises at least one address that matches a routing / transport capability of the service providing system. 12. The method of claim 9, wherein the location request comprises an indication of a protocol capability of the calling system. 13. The method of claim 11, further comprising the step of responding to the location confirmation request to confirm whether a valid virtual number parameter for the second user is stored in the home network. 12. The method according to 12. 14. If the valid virtual number parameter does not exist in the home network, requesting a routing address from the home system to the service providing system; and responding to the request for the routing address, Transmitting a number parameter and the protocol capability of the service providing system to the home system; and determining whether the protocol capabilities of the calling system and the service providing system match. If the protocol capabilities match, the virtual number parameter is transmitted to the calling system, and the calling system establishes the connection using an appropriate protocol and the virtual number parameter. 14. The method of claim 13, wherein . 15. The method of claim 14, further comprising performing a redirection procedure if the protocol capabilities do not match. 16. The method of claim 14, further comprising performing a proxy procedure if the protocol capabilities do not match. 17. If it is determined that a valid virtual number parameter exists,
Determining whether the protocol capabilities of the calling system and the service providing system match, wherein if the protocol capabilities match, the virtual number parameter is transmitted to the calling system. 14. The method of claim 13, wherein the calling system establishes the connection using an appropriate protocol and the virtual number parameter. 18. The method of claim 17, further comprising performing a redirect procedure if the protocol capabilities do not match. 19. The method of claim 17, further comprising performing a proxy procedure if the protocol capabilities do not match. 20. The method of claim 1, wherein the assignment of the virtual number parameter is monitored through use of the timer. 21. A system for providing interoperability between heterogeneous and incompatible networks, comprising: means for allocating a virtual number parameter; and using said virtual number parameter between said heterogeneous and incompatible networks. A system comprising means for establishing a connection, wherein the virtual number parameter is a general-purpose routing address. 22. The system of claim 21, wherein the virtual number parameter comprises addressing information for a plurality of protocols. 23. The system of claim 21, wherein the 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 according to claim 21, wherein said allocating means is a service providing network. 26. The system according to claim 21, wherein said allocating means is a home network. 27. The system according to claim 21, wherein said allocating means is a gateway. 28. The system according to claim 21, wherein said allocating means is a user terminal. 29. A means for transmitting a location confirmation request from a first user in a calling system to a home system of a second user located in a coverage area of a service providing system, and said call originating from said home system. Means for transmitting a response having the assigned virtual number parameter to a local system, wherein a connection is established between the calling system and the service providing system using the virtual number parameter. 22. The system of claim 21, wherein: 30. The virtual number parameter is a multi-protocol address assigned by the service providing system.
The described system. 31. The system of claim 29, wherein the virtual number parameter comprises at least one address that matches a routing / transport capability of the service providing system. 32. The system of claim 29, wherein the location request comprises an indication of a protocol capability of the calling system. 33. The apparatus of claim 33, further comprising: means for confirming whether a valid virtual number parameter for the second user is stored in the home network in response to the location confirmation request. 32. The system of claim 32. 34. A means for requesting a routing address from the home system to the service providing system when a valid virtual number parameter does not exist in the home network; Means for transmitting a number parameter and the protocol capability of the service providing system to the home system; and means for determining whether or not the protocol capabilities of the calling system and the service providing system match. If the protocol capabilities match, the virtual number parameter is transmitted to the calling system, and the calling system establishes the connection using an appropriate protocol and the virtual number parameter. 34. The system according to claim 33. 35. The system of claim 34, wherein the home system performs a redirection procedure if the protocol capabilities do not match. 36. The system of claim 34, wherein the home system performs a proxy procedure if the protocol capabilities do not match. 37. If it is determined that a valid virtual number parameter exists,
Means for determining whether the protocol capabilities of the calling system and the service providing system match, if the protocol capabilities match, the virtual number parameter is transmitted to the calling system. 34. The system of claim 33, wherein the calling system establishes the connection using an appropriate protocol and the virtual number parameter. 38. The system of claim 37, wherein the home system performs a redirect procedure if the protocol capabilities do not match. 39. The system of claim 37, wherein the home system performs a proxy procedure if the protocol capabilities do not match. 40. The system according to claim 29, wherein the means for transmitting the location confirmation request is a gateway. 41. The system according to claim 21, further comprising a timer for monitoring the virtual number parameter.