METHOD AND SYSTEM FOR INTEGRATING PBX FEATURES IN A WIRELESS NETWORK

Abstract: A system for incorporating legacy private branch exchange (PBX) features in a wireless network includes a base station (24) operable to communicate with a mobile station (12) over a wireless interface (48). The system also includes a gateway (34) coupled to the base station (24) and to the PBX (18) for instantiating the mobile station (12) to appear as a subscriber line to the PBX (18).

Description: METHOD AND SYSTEM FO INTEGRATING PBX FEATURES IN A WIRELESS NETWORK CROSS-REFERENCE TO RELATED APPLICATIONS This application is related to the following applications: U.S. Application Serial No. 09/128,553, filed on August 3, 1998, and entitled "A 'Plug and Play' Wireless Architecture Supporting Packet Data and IP Voice/Multimedia Services," pending; and U.S. Application Serial No. 09/219,539, filed on December 23, 1998, and entitled "Wireless Local Loop System Supporting Voice/IP," pending. All of the following applications are related: U.S. Application Serial No. 09/499,921, filed concurrently herewith, and entitled "Method and System for Interworking Voice Bearer Messages Between Circuit- Switched and Packet- Switched Networks," pending; U.S. Application Serial No. 09/499,923, filed concurrently herewith, and entitled "Method and System for Interworking Voice Signaling Messages Between Circuit-Switched and Packet-Switched Networks," pending; U.S. Application Serial No. 09/500,751, filed concurrently herewith, and entitled "Method and System for Incorporating Legacy Private Branch Exchange Features in a Wireless Network," pending; U.S. Application Serial No. 09/500,379, filed concurrently herewith, and entitled "Method and System for Providing User Mobility Between Public and Private Wireless Networks," pending; and U.S. Application Serial No. 09/499,922, filed concurrently herewith, and entitled "Method and System for Providing Management Protocol Mediation in Wireless Communications Networks," pending. These applications have been commonly assigned to Opuswave Networks, Inc. TECHNICAL FIELD OF THE INVENTION This invention relates generally to the field of telecommunications and, more specifically, to a method and system for incorporating legacy private branch exchange (PBX) features in a wireless network. BACKGROUND OF THE INVENTION Private branch exchanges, or PBXs, are well-known in the art of telecommunications. Corporations, organizations, and other enterprises typically use PBXs to provide internal telephone services to their personnel. The personnel may call one another without using an external switched public telephone network, although the PBX is coupled to the public telephone networks for making external local and long distance calls. Telephones are usually coupled to the PBX by wireline connections. PBXs also typically implement a variety of features, including call waiting, call forwarding, conferencing, and call blocking. Recently, interest in wireless networks has increased. Wireless networks allow mobile stations, or wireless units, to communicate over a wireless interface. The mobile station may be a wireless telephone communicating with a voice network over the wireless interface. The mobile station may also be a computer communicating with a data network over the wireless interface. Wireless communications may be over private or public networks. Operators of the wireless networks often wish to integrate the wireless networks into the existing PBXs and computer networks. The PBX and wireless network are usually separate networks since each of them often uses different protocols to transfer messages and manage elements of the network. The inability to fully integrate the wireless network with the PBX inhibits the wireless network from performing several key functions. Without full integration, mobile station users may have difficulty accessing the PBX. Also, the mobile station users may not be able to roam between the private wireless network and the public wireless network. The mobile station user cannot move in and out of the private wireless network while talking. Instead, the user has to terminate the call, move to the other network, and reestablish a connection. In addition, the inability to fully integrate the networks may force the mobile station users to have two different wireless phones, one for the private wireless network and one for the public wireless network. Further, to provide PBX features in a wireless network, the wireless network operator typically installs substantial hardware and/or software in the wireless network to provide these features. However, even though the PBX-like features are implemented in the wireless network, the PBX and the wireless network still remain separate. SUMMARY OF THE INVENTION In accordance with the present invention, a method and system for incorporating legacy PBX features in a wireless network is provided that substantially eliminates or reduces disadvantages and problems associated with previously developed systems and methods. A system for incorporating legacy private branch exchange (PBX) features in a wireless network is disclosed. The system comprises a base station operable to communicate with a mobile station over a wireless interface. The system also comprises a gateway coupled to the base station and to the PBX for instantiating the mobile station to appear as a subscriber line to the PBX. A method of incorporating legacy PBX features in a wireless network is also disclosed. The method comprises the step of coupling a mobile station to a base station using a wireless interface. The method also comprises coupling the base station to the PBX wherein the mobile station appears to the PBX as an extension of the PBX. A technical advantage of the present invention is that the wireless network can be fully integrated with the existing PBX. This means that the mobile stations can use the existing PBX to gain access to external voice networks like the public phone systems. Also, since the wireless network can work with an existing PBX, the invention eliminates any need to remove or replace the existing PBX. This reduces the cost of the equipment and the cost of installing the wireless network. In addition, the wireless network, once integrated into the other networks, can make use of the features currently implemented in the existing PBX. The wireless network can incorporate the features from the legacy PBX, eliminating the need to independently implement the features in the wireless network. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention, and for further features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: FIGURE 1 illustrates a private communications network coupled to existing public and private voice and data networks in accordance with the teachings of the present invention; and FIGURE 2 illustrates a packet switching subsystem of the private communications network coupled to existing private branch exchanges. DETAILED DESCRIPTION OF THE DRAWINGS Embodiments of the present invention and its advantages are best understood by referring to FIGURES 1 through 2 of the drawings, like numerals being used for like and corresponding parts of the various drawings. FIGURE 1 illustrates a private communications network coupled to existing public and private voice and data networks in accordance with the teachings of the present invention. Private network 10 comprises one or more mobile stations (MS) 12, a wireless subsystem (WSS) 14, a packet switching subsystem (PSS) 16, a private branch exchange (PBX) 18, and an Internet Protocol (IP) network 20. Mobile station 12 comprises any device capable of communicating with a base station 24 over a wireless interface 48. Mobile station 12 may comprise, for example, a Global System for Mobile communication (GSM) mobile station capable of delivering a circuit-switched speech service. Alternatively, mobile station 12 may comprise a portable computer with a microphone or a phone coupled to a wireless modem. Mobile station 12 may also comprise a computer and a phone coupled to a radio unit. In this document, the terms "couple," "coupled," and "coupling" refer to any direct or indirect connection between two elements within private network 10, whether or not the two elements are in physical contact with one another. Wireless subsystem 14 comprises one or more base station subsystems (BSS) 22. Each base station subsystem 22 comprises a base transceiver station (BTS) 24, also called a base station 24, and a wireless adjunct internet platform (WARP) 26. Base station 24 is coupled to WARP 26 by an interface 28. Base station 24 also provides bi-directional communication with mobile station 12 in a specified geographic area over wireless interface 48. Base station 24 is operable to transfer messages between mobile station 12 and WARP 26. Base station 24 may comprise, for example, one or more transceivers capable of transmitting and receiving circuit- switched messages from mobile station 12 over wireless interface 48. In one embodiment, base station 24 and mobile station 12 communicate using the GSM 04.08 signaling message and the 08.60 bearer message protocols. Wireless interface 48 couples mobile station 12 and base station 24. In this document, the term "wireless" designates the use of a radio or over-the-air interface to communicate with mobile station 12. Wireless interface 48 may comprise any of a number of available wireless interfaces capable of transferring circuit-switched messages between mobile station 12 and base station 24. In one embodiment, mobile station 12 and base station 24 communicate using the GSM General Packet Radio Service (GSM/GPRS) interface. In another embodiment, base station 24 and mobile station 12 communicate using the GSM Enhanced Data rates for GSM Evolution (GSM/EDGE) interface. WARP 26 is coupled to base station 24 by interface 28 and to IP network 20. WARP 26 allows users of mobile stations 12 to gain access to internal networks and to external voice and data networks. In one embodiment, WARP 26 communicates with mobile station 12 through base station 24 using a circuit-switched message protocol, and WARP 26 communicates with IP network 20 using a packet-switched message protocol. WARP 26 also provides interworking for the transmission of messages through private network 10. WARP 26 translates between the circuit- switched and the packet-switched protocols. In one embodiment, WARP 26 converts circuit-switched messages from mobile station 12 into packetized messages suitable for transmission over IP network 20. WARP 26 also converts packetized messages from IP network 20 into circuit-switched messages sent to mobile station 12. In a particular embodiment, WARP 26 uses the architecture specified in the International Telecommunications Union-Telecommunications (ITU-T) H.323 protocol standard for provisioning IP packet voice services. Interface 28 couples base station 24 and WARP 26. Interface 28 may be any of a number of available interfaces capable of transferring circuit-switched messages between base station 24 and WARP 26. Interface 28 may comprise, for example, a GSM Abis wireline interface. IP network 20 transmits and receives packet-switched messages from one address in IP network 20 to another address. IP network 20 may comprise any number of available packet-switched networks. IP network 20 may, for example, comprise a Local Area Network or a Wide Area Network. An IP phone 36 and a workstation 38 may also be coupled to IP network 20. IP network 20 may also be coupled to an external data network such as Internet 42 or to an external voice network like a public land mobile network (PLMN) 44. Packet switching subsystem 16 comprises a subscriber location register (SLR) 30, a gatekeeper (GK) 32, and a PBX gateway (GW) 34. Subscriber location register 30 is coupled to IP network 20. Subscriber location register 30 stores subscriber management information for each mobile station 12. Subscriber location register 30 stores general subscriber management information downloaded from PLMN 44. Subscriber location register 30 also stores each user's extension number, direct dial number, and any other information that is specific to private network 10. Subscriber location register 30 may comprise, for example, a SUN™ workstation with a database. PBX gateway 34 is coupled to IP network 20, a PBX 18, and a public switched telephone network (PSTN) 46. PBX gateway 34 communicates with IP network 20 using a packet-switched message protocol. PBX gateway 34 also communicates with PBX 18 or PSTN 46 using a circuit-switched message protocol. PBX gateway 34 provides the interworking functionality between packet-switched messages transmitted to and received from IP network 20 and circuit-switched messages transmitted to and received from PBX 18 or PSTN 46. In one embodiment, PBX gateway 34 communicates over IP network 20 using the ITU-T H.323 protocol standard, PBX gateway 34 communicates with PBX 18 using a PBX interface protocol, and PBX gateway 34 provides the interworking between the protocols. Gatekeeper 32 is coupled to IP network 20. Gatekeeper 32 provides call control services for mobile stations 12, WARPs 26, and PBX gateway 34. Gatekeeper 32 tracks the location of each mobile station 12, and gatekeeper 32 routes calls to and from the WARP 26 currently serving a particular mobile station 12. This allows users of mobile stations 12 to roam freely between geographic areas covered by different base stations 24. PBX 18 is coupled to PBX gateway 34, PLMN 44, and PSTN 46. PBX 18 may transmit and receive circuit-switched messages from PBX gateway 34, PLMN 44, and PSTN 46. PBX 18 may also communicate with a telephone 40 coupled to PBX 18. PBX 18 may be any of a number of available PBX networks capable of transmitting and receiving circuit-switched messages. PBX 18 may, for example, be a legacy PBX already installed within an existing private network. Line interface 50 couples PBX gateway 34 and PBX 18. Line interface 50 is operable to transfer circuit-switched messages between PBX 18 and PBX gateway 34. In one embodiment, line interface 50 may comprise an analog line or an Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) line. By using line interface 50 to couple PBX gateway 34 and PBX 18, each instantiation of a mobile station 12 may appear as a subscriber line to PBX 18. Mobile stations 12 appear to be extensions of PBX 18, rather than elements in a separate network. In this embodiment, private network 10 may incorporate features of PBX 18. Private network 10 may provide features and services to mobile stations 12 without the need to implement those features and services again in gatekeeper 32 or PBX gateway 34. The incorporated features may include station features and Advanced Network Features already implemented in PBX 18. For example, PBX 18 may handle service administration and billing operations for mobile stations 12. PBX 18 may also provide supplementary services, including call waiting, call forwarding, conferencing, and call blocking to mobile stations 12. FIGURE 2 illustrates one embodiment of packet switching subsystem 16 coupled to legacy PBXs 18. A WARP 68 is coupled to a gatekeeper 70. WARP 68 and gatekeeper 70 communicate using the ITU-T H.323 protocol and the ITU-T H.450 protocol. Gatekeeper 70 is also coupled to a gateway 72. Gatekeeper 70 and gateway 72 communicate using the ITU-T H.323 and H.450 protocols. Gateway 72 is further coupled to a PBX 74. Gateway 72 and PBX 74 communicate using the European Computer Manufacturers Association (ECMA) QSIG protocol. WARP 68 is also coupled to a gatekeeper/gateway unit 76. WARP 68 and gatekeeper/gateway unit 76 communicate using the ITU-T H.323 and H.450 protocols. Gatekeeper/gateway unit 76 is also coupled to PBX 74 and one or more other PBXs 78. Gatekeeper/gateway unit 76 is operable to perform the tasks of a gatekeeper 32 and a gateway 34 on a single platform. Gatekeeper/gateway unit 76 communicates with PBX 74 or other PBXs 78 using a Computer-Supported Telephony Applications (CSTA) protocol or a Telephony Application Programming Interface (TAPI) protocol. Other PBXs 78 represent legacy PBXs 18 previously installed within private network 10. In this embodiment, gatekeeper 70, gateway 72, and PBX 74 may be manufactured by a single vendor, ensuring compatibility between the elements. Other PBXs 78 may be manufactured by different vendors, and gatekeeper/gateway unit 76 is operable to communicate with each of other PBXs 78. Gatekeeper/gateway unit 76 is also operable to allow private network 10 to incorporate features from other PBXs 78 using line interface 50. Gatekeeper/gateway unit 76 may, for example, comprise a STARVOX™ gatekeeper/gateway unit. This embodiment illustrates the versatility of private network 10. For organizations without a legacy PBX 18, WARP 68, gatekeeper 70, and gateway 72 could be installed in private network 10 without the need for gatekeeper/gateway unit 76. In this case, there are no other PBXs 78, so there is no need for gatekeeper/gateway unit 76. In this embodiment, gatekeeper 70 and gateway 72 could implement PBX features for private network 10. Alternatively, PBX 74 could be installed and coupled to gateway 72 with line interface 50, allowing the incorporation of features from PBX 74. For organizations with many legacy PBXs 18, gatekeeper/gateway unit 76 ensures compatibility between private network 10 and other PBXs 78. Gatekeeper/gateway unit 76 also ensures that private network 10 may incorporate features from other PBXs 78 using line interface 50. Although an embodiment of the invention and its advantages are described in detail, a person skilled in the art could make various alternations, additions, and omissions without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims: WHAT IS CLAIMED IS: 1. A system for incorporating legacy private branch exchange (PBX) features in a wireless network, which provides services to a mobile station, characterized by: a base station (24) operable to communicate with a mobile station (12) over a wireless interface (48); and a gateway (34) coupled to the base station (24) and to the PBX (18) for instantiating the mobile station (12) to appear as a subscriber line to the PBX (18). 2. The system of Claim 1 , further characterized by a line interface (50) coupling the gateway (34) and the PBX (18). 3. The system of Claim 2, characterized in that the line interface (50) comprises an Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) line. 4. The system of Claim 2, characterized in that the line interface (50) comprises an analog line. 5. The system of Claim 1, further characterized by a wireless adjunct internet platform (WARP) (26) coupling the base station (24) and the gateway (34), the WARP (26) operable to communicate with the mobile station (12) through the base station (24) and to communicate with the PBX (18) through the gateway (34). 6. The system of Claim 5, further characterized by an Internet Protocol (IP) network (20) coupling the WARP (26) and the gateway (34), the IP network (20) operable to transmit messages from one address in the IP network (20) to another address. 7 The system of Claim 1, further characterized by a gatekeeper (32) coupled to the gateway (34). 8. A packet switching subsystem for incorporating legacy private branch exchange (PBX) features in a wireless network, which provides services to a mobile station, characterized by: a gateway (34) coupled to a base station (24) and to the PBX (18), the gateway (34) operable to communicate with the base station (24) and the PBX (18); and an interface (50) coupling the gateway (34) and the PBX (18) for instantiating a mobile station (12) communicating with the base station (24) to appear as a subscriber line to the PBX (18). 9. The packet switching subsystem of Claim 8, characterized in that the interface (50) comprises a line interface. 10. The packet switching subsystem of Claim 9, characterized in that the line interface (50) comprises an Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) line. 11. The packet switching subsystem of Claim 9, characterized in that the line interface (50) comprises an analog line. 12. The packet switching subsystem of Claim 8, further characterized by a gatekeeper (32) coupled to the gateway (34). 13. The packet switching subsystem of Claim 12, further characterized by an Internet Protocol (IP) network (20) coupling the gatekeeper (32) and the gateway (34), the IP network (20) operable to transmit messages from one address in the IP network (20) to another address. 14. A method of incorporating legacy private branch exchange (PBX) features in a wireless network, which provides services to a mobile station, characterized by: coupling a mobile station (12) to a base station (24) using a wireless interface (48); and coupling the base station (24) to the PBX (18) wherein the mobile station (12) appears to the PBX (18) as an extension of the PBX (18). 15. The method of Claim 14, characterized in that the base station (24) is coupled to the PBX (18) using a line interface (50). 16. The method of Claim 15, characterized in that the line interface (50) comprises an Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) line. 17. The method of Claim 15, characterized in that the line interface (50) comprises an analog line. 18. The method of Claim 14, characterized in that coupling the base station (24) to the PBX (18) comprises coupling a gateway (34) to the base station (24) and to the PBX (18). 19. The method of Claim 18, characterized in that coupling the gateway (34) to the base station (24) and the PBX (18) comprises coupling an Internet Protocol (IP) network (20) to the base station (24) and the gateway (34). 20. The method of Claim 18, further characterized by coupling a gatekeeper (32) to the gateway (34).

Inventors: MENON NARAYAN, MO RICHARD, MENON, NARAYAN, MO, RICHARD
Applicants: OPUSWAVE NETWORKS INC, OPUSWAVE NETWORKS, INC.
Application year: 2001
Main classification: H04Q7
IPC codes: H04W84, H04W92