WO1997028663A1

WO1997028663A1 - Telephone interexchange carrier selection in a wireless communication network

Info

Publication number: WO1997028663A1
Application number: PCT/US1997/001814
Authority: WO
Inventors: Anousheh Raissyan
Original assignee: Mci Communications Corporation
Priority date: 1996-02-01
Filing date: 1997-01-31
Publication date: 1997-08-07

Abstract

A wireless communication network for establishing a call path to a preferred interface gateway selected from a plurality of interface gateways to other networks providing service to call terminations not on the wireless network. The wireless network provides communications in GSM format and comprises a plurality of visitor location registers (106) each with a local database, and at least one common database (110) containing information relating to a plurality of mobile subscribers (101). At least a portion of the data relating to the subscriber in the common database is transcribed within the local database. The transcribed data includes a designation corresponding to the subscriber's selection of a wire-based network to be used for call terminations outside of the wireless network. This designation is used to establish the call path for outgoing calls to terminations outside the wireless network.

Description

T2LZPH0HB I-STESSZCSMIGB CAIUIIZR SELZCTIOH IS A WIBELZSS COHHUHICATION HETWORX

7IΣLD OF THE IHVEHTIOH

The present invention relates to the field of vireless communications. In particular, the invention relates to establishing a call path using the services of a designated interexchange carrier company in a multi-carrier telecommunications environment.

BACXGXOUND OP THE I2T7ENTICN Existing wire-based telecommunications networks comprise a plurality of local exchanges which are served by local telephone companies. Calls that originate within one exchange and terminate within another are handled at the origin and termination by the local telephone companies.. Batv^eis local telephone company connections, the call is handled by an interexchange carrier company (IXC) , which usually is separate from the local telephone company.

Within the current wire-based telephone system, more than one interexchange carrier provides service between any two local telephone exchange carriers (LEC) . Conventionally, the interexchange carrier for any given call is selected at the local telephone company. In most conventional systems, the originating subscriber can specify to the local telephone company a particular interexchange carrier to use for a call. One method that a subscriber may use to specify an interexchange carrier in a wire-based system is disclosed in U.S. Patents No. 4,577,066 to Bi cnte et al.. No. 4,565,903 to Riley, and No. 4,555,594 to Friedes et al. Each subscriber is allowed to pre-subscribe to any available interexchange carrier, and the information related to that carrier is stored as a record entry within a subscriber database. When a call terminating in another exchange is dialled by a subscriber, the local telephone company can use the subscriber's database entry to establish a call path to the previously selected interexchange carrier. The subscriber therefore need only dial the number of the recipient of a long distance call and the call is automatically connected through the selected interexchange carrier.

The above system presents significant ease-of-use tc a subscriber of the local telephone company, while the local telephone company incurs the cost of maintenance of the subscriber database records. Record retrieval and routing of calls to interexchange carriers occur at the same site, and thus the system is useful even for a very large number of subscribers.

In the case of wireless communication networks, it is also desirable to provide subscribers with the same features found in conventional wire-based communications networks. Automatic routing through an interexchange carrier is a popular feature, and attempts have been made to provide such selection to mobile subscribers.

One standard far wireless personal communications is the digital mobile telephone system GSM (Groupe Special Mobile) . The conventional GSM network is designed to support a large number of mobile subscribers (MS) . Calls are completed either between units on the mobile network, or between an MS and a destination on another network, possibly through an interexchange carrier. Switching and routing is controlled based on subscriber data contained in a central database known as a home location register (HLR) . However, there is no provision in the GSM format for designating and routing a call through a selected interchange carrier.

The HLR sends and receives information from a number of visitor location registers (VLR's) , each of which may be associated with a mobile telephone switching office, also referred to herein as a mobile switching center (MSC) . The VLR's contain information on subscribers that are physically within a limited geographic area served by a corresponding VLR. Therefore, there are a large number of VLR's within a mobile network.

In some applications, a single HLR handles data for a mobile network covering a relatively large geographic area made up of the limited areas served by a large number of VLR's. Each VLR communicates with the HLR to update the location of the subscribers in the HLR database as they enter and leave the area of each VLR. Every time a MS is called, a gateway MSC (GMSC) must receive routing information (e.g. a routing number) from the HLR, and .the GMSC then participates in switching the call. In conventional GSM systems, a VLR has all the information necessary to establish a call path from one subscriber within its geographic area to another subscriber within its geographic area. It would be desirable to further enable the VLR to establish call paths from either a roaming or a local subscriber to fixed sites within the GSM network, particularly gateways to other networks. Where multiple VLR's must communicate with a single HLR site before each call is enabled, the presence of a large number of VLR's increases both the signal processing and data storage and retrieval requirements at the HLR site, especially since all signalling should be substantially transparent to the subscribers. It therefore would be desirable to reduce the load on the HLR site and its communication links by enabling each VLR to route a call to an individual subscriber's selected interexchange carrier when the call destination is within another LEC.

SUMMARY OF TBS lHVϋHTIOH

Therefore, a principal object of the present invention is to provide a GSM wireless telecommunications network wherein services profile data for each subscriber on the wireless network includes selection of a preferred interexchange carrier. It is a further object of the invention to enable each subscriber to select a preferred interexchange carrier for calls outside the local wireless network and to route an outgoing call using the subscriber's selected carrier without requiring repeated communication with a central database site. These and other objects and advantages are achieved by the present invention, which comprises a system for accessing subscriber records within a GSM wireless communication network wherein subscriber data maintained at a central database site or at a plurality of local switching sites includes a field that designates a preferred interexchange carrier. Preferably the database at each local switching site contains subscriber records for all subscribers within the geographic area of the switching site, and these records are updated as subscribers move among the switching sites. Thus, a local switching site of the invention can route outgoing calls to the subscriber's selected interexchange carrier without communicating each time with a central database as the calls are processed.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the invention and its objects and advantages may be further understood from the detailed description below taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a diagram of the elements of a wireless communication network in accordance with the invention; Fig. 2 is a diagrammatic illustration of the signaling and messaging for creating a local data record in a VLR of the network of Fig. 1;

Fig. 3. is a table illustrating some of the data stored in the location registers in accordance with the invention; and. Fig. 4 is a diagrammatic illustration of the signaling and messaging for an outgoing call to an interexchange carrier from a VLR in the network of Fig. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the invention is described below as an improvement upon a digital mobile telephone system using the GSM format.

Fig. 1 of the drawings is a diagram of the elements of a wireless communication network in accordance with the invention. A number of mobile subscribers (MS) 101 are connected to the network through a base transceiver station and a base station center (BTS/BSC) 102, there being a BTS/BSC for each of the local switching sites 104. Corresponding mobile switch centers (MSC's) 105 and visitor location registers (VLR's) 106 control the local switch sites. All VLR's can communicate with at least one central database site 110 that includes a home location register (HLR) 112. Although not shown in Fig. 1, the HLR 112 may be incorporated into one of the mobile switching centers 105 such that central database site 110 would be coextensive with a local switching site 104.

The local switch site 104 can complete a call path either to another switch site on the same GSM network or to a gateway to another GSM network. The other GSM network may be an interexchange carrier (IXC) network 121. The IXC network 121 would in turn be connected to a local exchange carrier (LEC) 131 corresponding to the called number represented by land wire telephone 140.

More specifically, after determining that a roaming subscriber is currently within its service area, the serving MSC sends a registration notification (RN) to its VLR. The new serving MSC may detect a roaming subscriber's presence through automatic registration without a call request, call origination, call termination, or a service order. If the roaming subscriber has previously registered with an MSC within the domain of the VLR, the VLR may take no further action other than to record the identity of the MSC currently serving the roaming subscriber.

If the roaming subscriber is previously unknown to the VLR, or if the MSC registered information is not available at the VLR, the VLR sends a RN signal to the HLR associated with the roaming subscriber. The MSC recognizes this association based on the mobile identification number (MIN) reported by the roaming mobile subscriber's unit upon entering the new service area. The RN signal sent from the VLR to the MSC may be contingent upon an authorization response received from the HLR. For example, the roaming subscriber may not currently be a valid subscriber of the system in which the HLR is located.

If the roaming subscriber was previously registered elsewhere, the HLR sends a registration cancellation signal to the previously visited VLR. That prior serving VLR, upon receipt of the cancellation message, may remove all records of the roaming subscriber from its memory. The cancellation signal can be sent by the HLR at any time after it receives the RN signal. The new serving VLR creates an entry for the roaming subscriber in its internal data structure and may send a qualification request signal to the HLR in order to authenticate the roaming subscriber and determine the validation requirements. The VLR, if required, may then send a service profile request signal to the HLR to obtain the service profile record for the roaming subscriber. In accordance with the invention, this service profile record includes a preferred carrier identification code (PCIC) identifying the IXC selected and designated by the subscriber for calls terminating outside of the local network.

Thus, to complete a call from a mobile subscriber, a VLR 106 of the invention must first have a local service profile record for the subscriber. The local record is created in a VLR for serving a roaming subscriber by a location update procedure, which is illustrated in the diagram of Fig. 2. The local switch site 104 responds to a location update request 220 from a mobile subscriber 101 when the subscriber enters the coverage area of the switch. The update request may be initiated automatically or in response to the next service request.

After identification and authentication cycles 221 and 222, the VLR 106 communicates the new location (switch address) of the roaming subscriber to the HLR 112 in an "update location" message 230, which also includes the VLR number and the mobile identity number (MIN) assigned tq the subscriber's mobile unit. The HLR 112, after updating the central record 11 , communicates centrally maintained subscriber profile data 240 back to the VLR site 104. Profile data 240 is then stored in the VLR along with other data of the types illustrated in Fig. 3. According to the invention, one of the fields within the data 240 sent from the HLR to the local site is a preferred carrier identification code (PCIC) , which identifies the subscriber's choice of a preferred interexchange carrier (PIC) . After ciphering cycles 250 between MS 101 and local switch 104, VLR 106 sends an acknowledgement 260 confirming its receipt of the subscriber profile data 240 as shown diagram atically in Fig. 2.

When a mobile subscriber places an outgoing call, the called number may be on the same wireless network and within the area of the same local VLR, on the same wireless network and within the area of another VLR, or on a different network. The local VLR has all the information necessary to complete the call if both mobile subscribers are on the same VLR database. No communication with the HLR is necessary.

If the dialled digits correspond to a mobile subscriber that is not local to the same VLR, the calling VLR of the invention may retrieve the current location of the called mobile subscriber from the HLR. As an alternative where the called mobile subscriber is within the area of another (called) VLR on the same wireless network, the calling VLR may be programmed to obtain the location of that subscriber directly from the called VLR via direct communication links as represented by broken line arrows

107 and 108 in Fig. 1. In other words, the local switching sites 104 may be programmed to exchange that data so that no communication with the HLR is necessary.

If the digits that are dialled by the mobile subscriber correspond to a termination outside the same wireless network, th.e VLR will route the call to a gateway switch of the designated IXC network. A diagram of the signaling and messaging for an outgoing call to an IXC network is shown in Fig. 4. This preferably includes a service request 320, authentication and ciphering cycles 330, and a call setup 331, all between the MS 101 and the local switch site 104.

For destinations outside the local exchange, the VLR of the invention preferably uses the subscriber's PCIC within the local profile record to choose the destination IXC 121. As the addresses of the gateways to the IXC's are fixed within the network, the VLR of the invention can complete the call without communicating with the HLR as shown in steps 350 of the diagram of Fig. 4. These steps include call proceeding signaling and alert and connect signaling, followed by transmission of data and/or voice conversation. The selected IXC network then completes the call to the appropriate local exchange carrier (LEC) 131 corresponding to the called number.

Therefore, in a GSM wireless network according to the invention, a VLR may obtain on a one time basis and transcribe all data necessary to complete a call path to a fixed site on a distant LEC network. A lower overall communication load on the HLR may therefore be achieved by a relatively small increase in communication during location updates.

An alternative method of providing automatic selection of a preferred interexchange carrier is to store the carrier routing information at a central database site as part of the subscriber's service profile stored at this site. In routing each call, a local switch queries the central database and receives a preferred carrier identification code if the calling party has specified the use of a particular interexchange carrier. Whether using the local VLR database or the central database method cf the invention, the mobile subscriber enjoys the ease-of-use and preferred IXC provided by the subscriber's network profile, as is customary with wire-based networks.

While this invention has been described in the context of the preferred embodiments, it should be clear that the principles of the invention will work equally well with other telecommunications networks using the GSM format and with variations of the preferred embodiments that will be apparent to those skilled in the art. Many other modifications and alternatives are possible and will occur to those skilled in the art who become familiar with the instant disclosure. Such modifications and alternatives are intended to be within the scope of the invention as defined by the claims set forth below.

Claims

CLAIMS What is claimed is:

1. A wireless communication network for establishing a call path to an interface gateway selected from a plurality of

interface gateways to other networks providing service to call terminations not on the wireless network, said wireless network comprising:

a plurality of visitor location registers for handling communications with a plurality of mobile subscribers, each of the visitor location registers including a local database, and said communications including messages in GSM format;

at least one common database containing information relating to the plurality of mobile subscribers;

a recording system for providing, for each mobile subscriber whose communications are to be processed by at least one of the visitor location registers, a record within the local database of the processing visitor location register;

a messaging system for transcribing in said record within the local database at least a portion of the data relating to the subscriber that is contained in said common database, said data portion being in GSM format and including a designation corresponding to the subscriber's selection of an outside network to be used for call terminations outside of the wireless network; and,

a communication system for establishing, for outgoing calls to terminations outside the wireless network, a call path to an interface gateway corresponding to the subscriber's

selection of the outside network by using said designation within the local database record of the visitor location register.

2. A network according to claim 1, wherein said record in the processing visitor location register is provided in response to direct communications between said common database and said processing visitor location register.

3. A network according to claim 1, wherein said record in the processing visitor location register is provided in response to direct communications between said processing visitor location register and another one of said plurality of visitor location registers.

4. A method for establishing a call path from a wireless communication network to an interface gateway selected from a plurality of interface gateways to other networks providing service to call terminations not on the wireless network, said wireless network having a plurality of visitor location registers for handling communications with a plurality of mobile

subscribers and including visitor location registers each with a local database, and at least one common database containing information relating to the plurality of mobile subscribers, and said method comprising:

establishing, for each mobile subscriber whose communications are to be processed by at least one of the visitor location registers, a record within the local database of the processing visitor location register, said communications

including messages in GSM format;

transcribing in said record within the local database at least a portion of the data relating to the subscriber that is contained in said common database, said data portion being in GSM format and including a designation corresponding to the

subscriber's selection of an outside network to be used for call terminations outside of the wireless network; and,

establishing, for outgoing calls to terminations outside the wireless network, a call path to an interface gateway corresponding to the subscriber's selection of the outside network by using said designation within the local database record of the visitor location register.

5. A method according to claim 4, wherein said record in the processing visitor location register is provided in response to direct communications between said common database and said processing visitor location register.

6. A method according to claim 4, wherein said record in the processing visitor location register is provided in response to direct communications between said processing visitor location register and another one of said plurality of visitor location registers.