Abstract:
A method and system enables communications between a switched telephone network and a wireless network comprising a plurality of Mobile Switching Centers (MSCs). Each MSC is connected by respective interfaces to a broadband packet network used for the transfer of bearer traffic between the MSCs, and controls wireless communications with a respective plurality of wireless transceivers. The switched telephone network and the wireless network are interconnected by at least one media gateway for conveying bearer traffic between the switched telephone network and the broadband packet network. The system comprises a location register and a call manager. The location register is adapted to store, in respect of each wireless transceiver, information identifying a respective current MSC controlling communications with the wireless transceiver. The, call manager is adapted to: query the location register to obtain the information identifying the current MSC respecting the selected wireless transceiver; and enable a communications path across the broadband packet network between an inbound media gateway and the current MSC. The advantages include simplified routing, congestion reduction and reduced cost of infrastructure to support a rapidly expanding wireless subscriber base.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 09/543,328, filed Apr. 5, 2000 now U.S. Pat. No. 6,724,801. 
    
    
     MICROFICHE APPENDIX 
     Not Applicable. 
     TECHNICAL FIELD 
     The present invention relates to wireless communications networks and, in particular, to a method and system for enabling communications between a switched telephone network and a wireless network. 
     BACKGROUND OF THE INVENTION 
     In recent years, there has been an exponential increase in demand for wireless communications services, which was initiated by the development of cellular telephones. Cellular telephones permit subscribers to initiate telephone calls to other mobile subscribers or fixed stations in the Public Switched Telephone Network (PSTN), or to receive calls from either of those sources. Typically, communications between a subscriber using a wireless transceiver and a called station, is mediated by a Mobile Switch Center (MSC), which functions as a Service Switching Point (SSP) in the PSTN. MSCs control wireless communications with each wireless transceiver operating within a service area covered by the MSC. In order to provide wireless communication services over a large geographic area, it is common to divide the coverage area of the wireless network into discrete service areas (cells) several of which are collectively served by a respective MSC. MSCs operated by a wireless communications service provider are commonly interconnected by time division multiplexed (TDM) trunk facilities. Each subscriber of wireless telecommunications services is assigned a telephone number by the service provider associated with one of the MSCs. That MSC serves as a home MSC for the subscriber. The address (telephone number) of the subscriber&#39;s wireless transceiver is recorded in a home location register (HLR) maintained by the home MSC. Calls directed to the subscriber&#39;s address are routed using translation tables in the PSTN to the home MSC. 
     In order to enhance mobility of the subscriber, the HLR also contains information identifying a current location of the subscriber&#39;s wireless transceiver. As the subscriber roams from one cell to another, control of wireless communications with the wireless transceiver is transferred to the MSC serving the cell within which the wireless transceiver is located. The address of the “current MSC” is recorded in the HLR maintained by the home MSC of the wireless transceiver as the current location of the wireless transceiver. With this arrangement, an inbound call destined for a subscriber&#39;s wireless transceiver is automatically routed to the home MSC. Upon receipt of the call set-up messages, the home MSC queries its HLR to obtain the current location of the wireless transceiver, and then routes the inbound call to the current MSC, if it is different from the home MSC, in order to complete the call. 
     This conventional arrangement has a disadvantage in that, as the number of subscribers increases, substantial resources of each MSC become tied-up routing inbound calls to other MSCs to serve roaming subscribers. Additionally, as the number of MSCs increases, the size and complexity of the trunk facilities required to handle the inter-MSC traffic also increases. 
     In order to address these issues, it is known to designate one of the MSCs as a “Gateway MSC”, and route all inbound calls to wireless subscribers through the Gateway MSC. The Gateway MSC uses the call set-up messages for the inbound call to identify the home MSC, and queries the HLR maintained by the home MSC to obtain the current location of the called wireless transceiver. The Gateway MSC can then route the inbound call to the current MSC, bypassing the home MSC if the subscriber is roaming, so that the inbound call can be completed without requiring resources of the home MSC. This solution helps to reduce congestion in the mobile network. However, it also tends to increase the size and complexity of the interoffice trunking network because each MSC must be connected to a Gateway MSC in addition to being interconnected with the other MSCs. In addition, since all inbound traffic is routed through the Gateway MSC, congestion of trunks associated with the Gateway MSC is also increased as demand for wireless communications services grows. 
     Co-pending and co-assigned U.S. patent application Ser. No. 09/158,855, filed Sep. 23, 1998 and entitled TRANSIT TRUNK SUBNETWORK SYSTEM teaches the connection of SSPs to a broadband packet network (e.g. an Asynchronous Transfer Mode (ATM) or Internet Protocol (IP) backbone) which provides dynamic trunking between the SSPs over Switched Virtual Circuits (SVCs) set up through the broadband packet network. The application also teaches that the broadband packet network can be used for trunking between MSCs of a wireless network, thus providing a means of dramatically simplifying inter-MSC trunking by replacing interoffice TDM trunks with broadband packet network facilities. However, this solution relies on a Gateway MSC through which inbound calls are routed in order to enable identification of home MSCs and querying of the associated HLRs to determine a current location of called wireless subscribers. The Gateway MSC therefore becomes a bottleneck to traffic handling as the number of mobile subscribers increases. Alternatively, the Gateway MSC functionality may be distributed among the MSCs in the wireless network. However, this solution has a disadvantage in that the Gateway MSC functionality must be installed and maintained in each of the distributed Gateway MSCs. This contributes to operating overhead and capital expense. 
     Accordingly, there exists a need for a low cost and highly scalable means for enabling communications between wireline and wireless subscribers. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a method and system for enabling communications between a switched telephone network and a wireless telephone network in which inbound calls can be routed to the wireless network through any one of a plurality of gateways. 
     A further object of the present invention is to provide a method and system for enabling communications between a switched telephone network and a wireless network, in which an inbound call entering the wireless network through an inbound gateway is trunked through a broadband packet network and an outbound gateway to a specific MSC controlling wireless communications with a destination wireless transceiver. 
     Accordingly, the present invention provides a system for enabling communications between a switched telephone network and a wireless network comprising a plurality of Mobile Switching Centers (MSCs). Each MSC is connected by respective gateways to a broadband packet network used for the transfer of bearer traffic between the MSCs, and controls wireless communications with a respective plurality of wireless transceivers (cellular phones, personal computer with wireless communication capability, etc). The switched telephone network is interconnected by at least one gateway to the broadband packet network for conveying bearer traffic between the wireline network and the broadband packet network. The system comprises a location register and a call manager. The location register is adapted to store, in respect of each wireless transceiver, information identifying the MSC currently controlling communications with the wireless transceiver. The call manager is adapted to query the location register to retrieve the information identifying the MSC currently serving a selected wireless transceiver. The call manager enables a communications path across the broadband packet network between a selected gateway and the MSC. 
     The invention also provides a method of enabling communications between a switched telephone network and a wireless telephone network comprising a plurality of mobile switching centers (MSCs). Each MSC is connected by respective gateways to a broadband packet network used for the transfer of bearer traffic between the MSCs, and each MSC controls wireless communications with a respective plurality of wireless transceivers. The switched telephone network is interconnected by at least one gateway to the broadband packet network for conveying bearer traffic between the switched telephone network and the broadband packet network. The method comprises a first step of providing a location register for storing, in respect of each wireless transceiver, information identifying an MSC serving each wireless transceiver at the time of a query. In a second step, the location register is queried to obtain the information identifying the MSC serving a selected wireless transceiver. In a third step, a communications path is enabled across the broadband packet network between a selected gateway interfacing the switched telephone network and a selected gateway interfacing the MSC serving the selected transceiver. 
     The location register may comprise a centralized home location register (HLR) containing information identifying a respective MSC serving each wireless transceiver in the wireless network. The location register may be co-resident with the call manager, or remote from the call manager. The call manager may be adapted to query the location register via a Common Channel Signaling (CCS) network or via the broadband packet network. 
     Alternatively, the location register may comprise a plurality of Home Location Registers (HLRs), each HLR being associated with a respective home MSC and containing information respecting predetermined ones of the wireless transceivers. In this case, the call manager is preferably adapted to: select one of the plurality of HLRs; and query the selected HLR via one or more of the broadband packet network and a Common Channel Signaling (CCS) network. Selection of the HLR can be based on information identifying the selected wireless transceiver. 
     Preferably, the call manager is connected to a common channel signaling (CCS) network and is assigned a point code to enable call setup messages to be addressed to the call manager for setting up communications paths across the broadband packet network. 
     For an inbound call to a selected wireless transceiver, the call manager is preferably responsive to call setup messages to set up a communications path across the broadband packet network between an inbound gateway interfacing the switched telephone network and an outbound gateways interfacing the MSC serving the selected wireless transceiver. The call setup messages may be conventional Integrated Services Digital Network User Port (ISUP) messages including information identifying the selected wireless transceiver. The call manager is preferably adapted to query the location register, using the information identifying the selected wireless transceiver, to obtain information identifying the MSC currently serving the selected wireless transceiver. The call manager may be further adapted to send a call set-up message including information identifying the selected wireless transceiver to the serving MSC to enable completion of the call to the selected wireless transceiver, and to send connection request messages to the inbound gateway and the outbound gateway to set up a communications path across the broadband packet network between the inbound gateway and the outbound gateway. 
     For an outbound call originating from a wireless transceiver, the call manager is preferably responsive to call setup messages to set up a communications path across the broadband packet network between the gateway interfacing the MSC serving of the selected wireless transceiver and an outbound gateway interfacing the switched telephone network. The call setup messages are preferably ISUP messages including information identifying the MSC serving the wireless transceiver, and a destination address on the switched telephone network. The call manager may be further adapted to select one of the plurality of gateways as the outbound gateway and send connection request messages to the outbound gateway and the gateway interfacing the MSC to set up a communications path across the broadband packet network between the gateway interfacing the MSC and the outbound gateway. Thereafter, the call manager sends a call set-up message over the CCS network to the switched telephone network, to set up a connection across the switched telephone network between the outbound gateway and the destination address. 
     Selection of the outbound gateway may be made on a basis of geographical proximity to the destination address in the switched telephone network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
         FIG. 1  is a schematic diagram illustrating a prior art configuration of a wireless communications network in which traffic inbound from the Public Switched Telephone Network (PSTN) is routed through a Gateway MSC; 
         FIG. 2  is a schematic diagram illustrating another prior art configuration of a wireless communications network in which time division multiplexed (TDM) trunking shown in  FIG. 1  has been replaced by a broadband packet network; 
         FIG. 3  is a schematic diagram of a system in accordance with a preferred embodiment of the present invention for enabling communications between a switched telephone network and a wireless network; 
         FIGS. 4   a-b  are message-flow diagrams schematically illustrating the principle messages exchanged between the components of the system shown in  FIG. 3  for calls inbound from the PSTN to a wireless transceiver; and 
         FIGS. 5   a-b  are message-flow diagrams schematically illustrating the principle messages exchanged between the components of the  FIG. 3  for calls outbound from a wireless transceiver to the PSTN. 
     
    
    
     It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention provides a means of enabling communications between a switched telephone network (e.g. the PSTN) and a wireless communications network. Wireless communications services are currently provided by a number of competing service providers, each of which maintains a respective wireless network providing wireless communications services within a coverage area. As shown in  FIG. 1 , the wireless network  2  typically includes a plurality of mobile switch centers (MSCs)  4   a-d  (four of which are shown in  FIG. 1 ) which are well known in the art. Each MSC  4   a - 4   d  controls wireless communications for wireless transceivers  6  (only one of which is shown in  FIG. 1 ) within a respective service area, typically via one or more Base Transceiver Stations (BTS)  8  and, possibly, one or more Base Station Controllers (BSC)  10 . In general, each MSC  4  is capable of controlling a plurality of BSCs  10 , each of which is capable of controlling a respective plurality of BTSs  8 . However, for ease of illustration, only one base station controller  10  and one base transceiver station  8  are shown. 
     Each subscriber has a Wireless Transceiver (WT)  6 , for example a cellular telephone or a personal communications system (PCS), to facilitate wireless communications. Each wireless transceiver  6  is assigned by the communications service provider to a home MSC which maintains a record related to the wireless transceiver in a home location register (HLR)  12   a-d.    
     As the subscriber roams within the coverage area of the wireless network  2 , the wireless transceiver  6  may leave the service area of the home MSC  4  and enter the service area of another MSC  4  in the network  2 . When this occurs, its record in the HLR  12  is dynamically updated with information concerning the location of the wireless transceiver  6 . Typically, this information is an address of an MSC  4  serving the wireless transceiver, which is an MSC  4  that controls the service area within which the wireless transceiver  6  is located. As is known in the art, each MSC also maintains a Visitor Location Register (VLR)  14   a-d  in which it records information identifying roaming wireless transceivers that are currently within the service area that the MSC controls. 
     For example, in the arrangement illustrated in  FIG. 1 , the wireless transceiver  6  may be assigned to MSC  4   a  as its home MSC. However, the wireless transceiver  6  has roamed into the service area of MSC  4   d , and thus the address of MSC  4   d  will be entered in the HLR  12   a  as the location of the wireless transceiver  6 . 
     Trunking of inter-MSC traffic is typically accomplished by means of a complex mesh of interoffice trunks  16  that interconnect each of the MSCs  4   a-d  to each of the other MSCs  4   a - 4   d . In order to reduce resource demand on each of the MSCs  4   a-d , a gateway MSC  18  can be provided to handle inbound calls originating in the PSTN and destined for wireless transceivers. Thus, for example, an inbound call destined for a selected wireless transceiver  6 , is routed through the PSTN to the Gateway MSC  18 . Upon receipt of a call set-up message (e.g. a conventional ISUP IAM message), the Gateway MSC  18  uses information in the call set-up message to find the address of the home MSC  4   a  of the wireless transceiver  6 . The Gateway MSC  18  then queries the HLR  12   a  maintained by the home MSC  4   a  (e.g. by means of a conventional query message to the home MSC  14   a ) in order to obtain information identifying the location of the wireless transceiver  6  (e.g. in this case the address of the MSC  4   d ). Based on the information identifying the location of the wireless transceiver, the Gateway MSC then routes the inbound call to the current MSC  4   d  for termination in a conventional manner using the interoffice trunks  16  that interconnect the MSCs  4   a-d.    
     Each MSC  4   a-d  is configured as a Service Switching Point (SSP) in the PSTN. Thus, an outbound call originating at a wireless transceiver  6  and destined for a termination in the PSTN can be routed directly from the MSC  4   d  to the PSTN. 
     Alternatively, the Gateway MSC functionality can be distributed among the MSCs  4   a - 4   d  so that an inbound call destined for a selected-wireless transceiver  6 , is routed through the PSTN to a predetermined one of the Gateway MSCs  4   a-d  based on, for example, the home address of the wireless transceiver. Upon receipt of the call set-up message, the distributed Gateway MSC  4   a , for example, uses information in the call set-up message to find the address of the home MSC  4   d , for example, of the wireless transceiver  6 . The distributed Gateway MSC  4   a  then queries the HLR  12   d  maintained by the home MSC  4   d  in order to obtain information identifying the location of the wireless transceiver  6 . In this example, the wireless transceiver is in an area served by the home MSC  4   d . Based on the information identifying the location of the wireless transceiver, the distributed Gateway MSC  4   a  then routes the inbound call to the home MSC  4   d  for termination in a conventional manner. 
     As shown in  FIG. 2 , inter-MSC trunking has been dramatically simplified by replacing the interoffice trunks  16  with a broadband packet network  20  as described in the co-assigned U.S. patent application Ser. No. 09/158,855. For this purpose, each of the MSCs  4   a-d , as well as the Gateway MSC  18 , are provided with an interface  22  (e.g. a media gateway (MG)) for converting Time-Division Multiplexed (TDM) Pulse Code Modulated (PCM) signals of the PSTN to a data format of the broadband packet network. One or more additional MGs  24  may also be provided to interconnect additional SSPs  26  of the PSTN to the broadband packet network  20  in order to carry outbound traffic originating from wireless transceivers  6  and destined for the PSTN. 
     Inbound calls are routed to the Gateway MSC  18  which determines the address of the home MSC  4   a  of the called wireless transceiver  6  and queries the associated HLR  12   a , as described above with respect to FIG.  1 . The inbound call is then routed to the current MSC  4   d  via a switched virtual connection (SVC) set-up through the broadband packet network  20  by a call manager  28 . The detailed inter-workings of the MGs  22  and the interaction between the Gateway MSC  18 , the call manager  28 , and the MSC  4   d  to enable routing of signals through the broadband packet network  20  are described in detail in U.S. patent application Ser. No. 09/158,855, and is therefore not described in detail. 
     As shown in  FIG. 3 , the present invention provides an improved arrangement for enabling communications between the PSTN and the wireless network  2 . In accordance with the present invention, the HLR functionality of the Gateway MSC  18  ( FIGS. 1 and 2 ) is relocated to the call manager  30 , thus rendering the Gateway MSC  18  redundant. Elimination of the Gateway MSC  18  enables inbound calls to be routed to the broadband packet network  20  through any SSP  26   a-c  of the PSTN provided with an MG  24   a-c  to the broadband packet network  20 . 
     Since inbound and outbound calls may be routed through any of a plurality of MG connections ( 24   a ,  26   a - 24   c ,  26   c ), points of congestion in the PSTN are reduced and scalability of the wireless network  2  is enhanced. In the embodiment shown in  FIG. 3 , each of the MSCs  4   a-d , as well as the associated base station controllers  10  and base transceiver stations  8 , can be of a conventional design. Similarly, the content and functionality of the respective visitor location registers  14   a-d  maintained by each MSC  4   a-d  can be conventional. The home location register  12 , which contains information identifying the location of each wireless transceiver  6  in the wireless network, may be distributed among the MSCs  4   a-d  in a conventional manner. If so, the call server will query the appropriate HLR based on the phone number of the mobile transceiver. Alternatively, the HLR  12  may be consolidated (as shown in  FIG. 3 ) to facilitate access by the call manager  30 . A consolidated HLR  12  can be co-resident with the call manager  30 , or stored at a remote location and accessed by the call manager  30  through either the CCS network or the broadband packet network  20 . The operation of the principle elements of the system shown in  FIG. 3  is described below for inbound and outbound calls with reference to  FIGS. 4   a-b  and  5   a-b , respectively. 
       FIGS. 4   a-b  are schematic diagrams of the principal messages exchanged during the set-up and release of an inbound call connection to a wireless transceiver  6  from a telephone handset  32  connected to a caller served by SSP  34  in the PSTN. In step  100 , the telephone handset  32  is operated by a user (not shown) to dial digits to initiate the call. The dialed digits are transmitted over a subscriber loop (not illustrated) to the SSP  34  in a manner well known in the art. On receipt of the dialed digits, the SSP  34  queries translation and routing tables (not shown) to determine how the call should be routed. The translation tables may be local translation tables or may require a query to a Service Control Point (SCP) not shown. After translation and routing (step  102 ), the SSP  34  determines that the call should be routed to an SSP  26   a  which can reach the mobile network via the broadband packet network  20 . The SSP  34  therefore formulates an ISUP IAM and forwards it in step  104  to the inbound SSP  26   a.    
     On receipt of the ISUP IAM, gateway SSP  26   a  queries translation and routing tables (not shown) to determine how the call should be routed (step  106 ). These translation and routing tables may also be local tables or may require a query to a Service Control Point (SCP) (not shown). On translation, the inbound SSP  26   a  determines that the call should be routed to a Point Code of the call manager  30  which acts as the entry point to get access to the MSC. As will be understood by those skilled in the art, there may be more than one call manager  30  associated with the broadband packet network  20 , each call manager  30  being identified by a unique point code. 
     The gateway SSP  26   a  therefore formulates an ISUP IAM and forwards it in step  108  to the call manager  30 . On receipt of the ISUP IAM, the call manager  30  translates the dialed number and queries the HLR  12  to obtain information respecting which of the MGCs  4   a - 4   b  is currently serving the mobile transceiver, in this example the MSC  4   d  (steps  110  and  112 ). The call manager  30  also determines an address (in the broadband packet network) of the MG  22   d  connecting to the MSC  4   d . Consequently, the call manager formulates an IAM Advisory message which it forwards to the MG  22   d  (step  114 ). An IAM Advisory message is also formulated and sent to MG  24   a  via the broadband packet network in step  116 . On receipt of the IAM Advisory messages, MGs  22   d ,  24   a  return IAM Acknowledge messages in steps  118 ,  120 , respectively. On receipt of the IAM Acknowledge messages, the call manager  30  formulates connection request messages which are forwarded to the respective MGs  22   d ,  24   a  in steps  122  and  124 . The IAM Advisory message sent in step  114  to MG  22   d  contained the broadband packet network address of MG  24   a . Consequently, MG  22   d  is enabled to set up a connection (a Switched Virtual Circuit (SVC), for example), backwards through the broadband packet network to the MG  24   a . This is initiated by sending a SVC request message in step  126 . This message is processed by the various elements in the broadband backbone network  20  using methods which are well known to establish an end to end connection. Eventually the message  126  reaches the MG  24   a  which responds with a SVC acknowledge message in step  128  indicating that the connection has been set up. Again, message  128  is processed by the same elements in the broadband backbone network  20  using methods which are well known. Meanwhile, the call manager  30  formulates an ISUP IAM containing the dialed digits and forwards the ISUP IAM to the current MSC  4   d  in step  130 . On receipt of the ISUP TAM, the MSC  4   d  may extract the dialed digits and query (step  132 ) its Visitor Location Register (VLR)  14   d  to determine whether the wireless transceiver  6  is in fact located within its service area. If the result of the query is affirmative, the VLR  14   d  returns an enabled signal in a response message (step  134 ). Otherwise, the MSC  4   d  returns an ISUP Release message (not shown) to the call manager  30  to end the inbound call connection request. In this example, an affirmative response is returned by the VLR  14   d  at step  134 . Consequently, the MSC  4   d  sets-up a wireless connection (steps  135   a-e ) with the wireless transceiver  6  and then returns an Address Complete (ACM) ISUP message in step  136  to the call manager  30 . On receipt of the ACM, the call manager  30  sends respective ACM Advisory messages to the MGs  22   d ,  24   a  in steps  138  and  140 . These messages are acknowledged in steps  142  and  144 . Meanwhile, the call manager  30  forwards the ACM message to the SSP  26   a  in step  148  which in turn forwards the ACM message to the SSP  34  in step  148 , which connects the local loop that serves the telephone handset  32  to complete the circuit to the MSC  4   d.    
     On successful completion of the wireless connection path with the wireless transceiver  6  (e.g. the subscriber presses a “receive” button of the wireless transceiver  6 , at step  150 ), the MSC  4   d  formulates an ISUP Answer (ANM) message which it returns to the call manager  30  in step  152 . On receipt of the ANM message, the call manager  30  sends ANM Advisory messages to the respective MGs  22   d ,  24   a  in steps  154 ,  156  and receives Acknowledgements in steps  158 ,  160 . The call manager  30  then forwards the ANM message to SSP  26   a  in step  162 , which forwards the ANM message to the SSP  34  in step  164 . On receipt of the ANM message, the SSP  34  may start a billing record for the call, if appropriate. 
     After the caller and subscriber have completed the communications session, the caller places their telephone handset  32  “on-hook” in step  166  ( FIG. 4   b ). On receiving the on-hook signal, the SSP  34  formulates an ISUP Release (REL) message which it forwards to the SSP  26   a  (step  168 ), which in turn forwards the ISUP REL message to the call manager  30  in step  170 . On receipt of the REL message, the call manager  30  sends REL Advisory messages and receives REL Acknowledge messages to the respective MGs  22   d ,  24   a  (steps  172 - 178 ). The call manager  30  then sends the REL message on to the MSC  4   d  in step  180 . On receipt of the REL message, the MSC  4   d  releases the wireless connection with the wireless transceiver  6  and performs subscriber billing functions, as required (step  182 ). The MSC  4   d  then formulates an ISUP Release Complete (RLC) message which it sends in step  184  to the call manager  30 . Meanwhile, the call manager  30  has sent an RLC message in step  186  to the SSP  26   a  (which is forwarded to the SSP  34 , in step  188 ) and an RLC Advisory message in step  190  to the MG  24   a . On receipt of the RLC message in step  184  from the MSC  4   d , the call manager  30  sends an RLC Advisory message in step  192  which completes release of resources used in the inbound call connection. 
       FIGS. 5   a-b  are schematic diagrams of the principal messages exchanged during the set-up and release of an outbound call connection from a wireless transceiver  6  to a telephone handset  32  connected to a caller-facing SSP  34  in the PSTN. In step  200 , the wireless transceiver  6  is operated by the subscriber (not shown) to set up a wireless connection path with the MSC  4   d  and dial digits to initiate the call in a manner well known in the art. The dialed digits are transmitted over the wireless connection to the MSC  4   d , again in a well known manner. On receipt of the dialed digits, the MSC  4   d  queries translation and routing tables (not shown) to determine how the call should be routed. The translation and routing tables may be local tables or may require a query to a Service Control Point (SCP). On translation (step  202 ), the MSC  4   d  determines that the call should be routed to a Point Code of the call manager  30 . 
     The MSC  4   d  therefore formulates an ISUP IAM and forwards it in step  204  to the call manager  30 . On receipt of the ISUP IAM, the call manager  30  translates the dialed number and determines which SSP is to serve as a gateway SSP  26   a  for the call, in step  206 . The call manager  30  also determines the address (on the broadband packet network) of the MG  24   a  serving that gateway SSP  26   a . Consequently, the call manager formulates an IAM Advisory message which it forwards via the broadband packet network to the MG  24   a  (step  208 ). An IAM Advisory message is also formulated and sent to MG  22   d  via the broadband packet network (step  210 ). On receipt of the IAM Advisory messages, MGs  24   a ,  22   d  return IAM Acknowledge messages in steps  212 ,  214 , respectively. On receipt of the IAM Acknowledge messages, the call manager  30  formulates connection request messages which are forwarded to the respective MGs  24   a ,  22   d  in steps  216  and  218 . The IAM Advisory message sent in step  208  to MG  24   a  contained the broadband packet network address of MG  22   d . Consequently, MG  24   a  is enabled to set up a connection (a Switched Virtual Circuit (SVC), for example), backwards through the broadband packet network to the MG  22   d  serving the MSC  4   d . This is initiated by sending a SVC request message in step  220 . The MG  22   d  responds with a SVC Acknowledge message in step  222  indicating that the connection has been set up. Meanwhile, the call manager  30  formulates an ISUP IAM containing the dialed digits and forwards the ISUP IAM to the gateway SSP  26   a  in step  224 . On receipt of the ISUP IAM, the gateway SSP  26   a  translates the dialed digits and formulates a further ISUP IAM message to the SSP  34  in step  226 . On receipt of the ISUP IAM message, the SSP  34  extracts the dialed digits and tests the local loop which serves the telephone handset  32  to determine if the handset  32  is available (on-hook) (step  228 ). If so, the SSP  34  applies ringing to the local loop and returns an Address Complete (ACM) ISUP message. Otherwise, the SSP  34  returns an ISUP Release message to the outbound SSP  26   a  (which relays it to the call manager  30 ) to terminate the outbound call connection request. In this example, the local loop is determined to be available at step  228 . Consequently, the SSP  34  returns an Address Complete (ACM) ISUP message in step  230  to the gateway SSP  26   a . This ISUP ACM message is forwarded on to the call manager  30  in step  232 . On receipt of the ISUP ACM, the call manager  30  sends respective ACM Advisory messages to the MGs  24   a ,  22   d  in steps  234  and  236 . These messages are acknowledged in steps  238  and  240 . Meanwhile, the call manager  30  forwards the ACM message to the MSC  4   d  in step  242 . 
     When the called telephone handset  32  is taken “off-hook”, in step  244 , the SSP  34  formulates an ISUP Answer (ANM) message which it returns to the gateway SSP  26   a  in step  246 . The gateway SSP  26   a  forwards the ISUP ANM message to the call manager  30  in step  248 . On receipt of the ANM message, the call manager  30  sends ANM Advisory messages to the respective MGs  24   a ,  22   d  in steps  250 ,  252  and receives Acknowledgements in steps  254 ,  256 . The call manager  30  then forwards the ANM message to MSC  4   d  in step  258 . On receipt of the ANM message, the MSC  4   d  can start the billing record for the call. 
     After the subscriber and called party have completed the communications session, the subscriber ends the call in step  260  ( FIG. 5   b ). On receiving the “end” signal, the MSC  4   d  releases the wireless connection with the wireless transceiver  6  and formulates an ISUP Release (REL) message which it forwards to the call manager  30  in step  262 . On receipt of the REL message, the call manager  30  sends REL Advisory messages and receives REL Acknowledge messages to the respective MGs  24   a ,  22   d  (steps  264 - 270 ). The call manager  30  then sends the REL message on to the gateway SSP  26   a  in step  272 . The gateway SSP  26   a  passes the ISUP REL message to the SSP  34  (step  274 ) which disconnects the subscriber loop serving the called telephone handset  32 . The SSP  34  then formulates an ISUP Release Complete (RLC) message which it sends in step  276  to the gateway SSP  26   a . Meanwhile, the call manager  30  has sent an RLC message in step  278  to the MSC  4   d  and an RLC Advisory message in step  280  to the MG  22   d . On receipt of the RLC message in step  282  from the gateway SSP  26   a , the call manager sends an RLC. Advisory message in step  284  which completes release of resources used in the outbound call connection. 
     As will be understood by those skilled in the art, calls made to wireless transceivers from wireless transceivers are handled in the same way as described above. Translation tables in the MSCs  4   a-d  route ISUP IAM messages to the call manager  30 . The call manager  30  consults the HLR  12  to determine a current MSC serving the called wireless transceiver and sets up a call path through the broadband packet network  20  between the originating and current MSC Wireless call completion is thereby facilitated and call routing significantly simplified, regardless of where the call terminates in the wireless or the wireline networks. 
     As will also be understood by those skilled in the art, although the invention has been described with reference to an Asynchronous Transfer Mode (ATM) broadband packet network, other broadband network protocols could also be used with success. For example, the invention may also be implemented using an Internet Protocol (IP) network, or a Multi-Protocol Label Switching (MPLS) network. 
     As will be further understood by those skilled in the art, although the invention has been explained with reference to a common channel signaling network used for call control messaging, many other types of signaling network can also be used with success. For example, the signaling network may be an X.25 network, an ATM, IP or MPLS network, or any other data packet network adapted to convey signaling messages between network nodes. 
     The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.