Apparatus and method for directing calls to mobile station subscribers

• US 5,369,684 A
• Filed: 01/13/1994
• Issued: 11/29/1994
• Est. Priority Date: 04/27/1990
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hayes, John, Buhl, Nancy, Kallin, Harald
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Bost, Dwayne D.
• Application Number:
  US08/194,872
• Time in Patent Office: 320 Days
• Field of Search: 379/56, 379/57, 379/58, 379/59, 379/60, 379/63, 455/33.1, 455/33.2, 455/33.3, 455/33.4, 455/54.1, 455/54.2, 455/56.1
• US Class Current: 455/432.1
• CPC Class Codes: H04W 68/12 Inter-network notification

Abstract

The present invention provides a mobile communications system in which the home exchange of a mobile subscriber maintains information indicative of where the mobile subscriber might be found, Upon receipt of a call, the home exchange requests the exchange where the mobile is believed to be located to page it and then requests the answering exchange(s) to order the mobile to tune to a voice/traffic channel. Only after the successful completion of this process does the answering exchange report this to the home exchange which then orders routing of the call through the network.

Claims

1. In a mobile communication system having a plurality of exchanges within which at least one mobile station may roam and which are connected with one another by PSTN lines, a method for routing an incoming call from an interrogation exchange to the called mobile station, comprising:

obtaining information as to the anticipated location of the mobile station;

paging the called mobile station in at least one of a plurality of locations based upon said anticipated location information in response to the receipt of an incoming call for said mobile station by said interrogation exchange;

receiving a page response from the paged mobile station at one of said plurality of locations;

designating to said mobile a voice channel to which to tune at said one of said plurality of locations in response to receiving a page response from the paged mobile;

sending information identifying the explicit location of the called and waiting mobile to the interrogation exchange via said private data lines in response to receiving an indication at said one of said plurality of locations that said mobile has tuned to he designated voice channel and is waiting on said voice channel; and

routing the call for said mobile via said PSTN communications lines from said interrogation exchange to the exchange in which said mobile station is located and waiting on a voice channel in response to receipt of information identifying the explicit location of said mobile.

2. A mobile communications system comprising:

at least one mobile station;

a home exchange associated with said at least one mobile station;

one or more additional exchanges within which said at least one mobile station may be presently located;

means for maintaining information indicative of where said at least one mobile station may be located;

private data lines connecting said home and one or more additional exchanges for passing signals therebetween;

PSTN communications lines connecting said exchanges;

paging means, responsive to receipt of a call by an interrogation exchange directed to said at least one mobile station, for selectively paging said at least one mobile station in at least one of a plurality of locations in said home exchange and said one or more additional exchanges;

means at each of said plurality of locations for receiving a page response from the paged mobile station;

means at each of said plurality of locations and responsive to receiving a page response from the paged mobile for designating to said mobile a voice channel to which to tune;

means responsive to receiving an indication at one of said plurality of locations that said mobile has tuned to the designated voice channel and is waiting on said voice channel, for sending information identifying the explicit location of the called and waiting mobile to the interrogation exchange via said private data lines; and

means responsive to receipt of information identifying the explicit location of said mobile for routing the call for said mobile via said PSTN communications lines from said interrogation exchange to the exchange in which said mobile station is located and waiting on a voice channel.

3. A mobile communication system as set forth in claim 2, also including:

means responsive to a failure to identify the explicit location of said at least one mobile for notifying the calling party of failure of the call.

4. In a mobile communication system having a plurality of exchanges within which at least one mobile station may roam and which are connected with one another by both private data lines for passing signals therebetween and PSTN communications lines, a method for routing an incoming call from an interrogation exchange to the called mobile station, comprising:

obtaining information as to the anticipated location of the mobile station;

paging the called mobile station in at least one of a plurality of locations based upon said anticipated location information in response to the receipt of an incoming call for said mobile station by said interrogation exchange;

receiving a page response from the paged mobile station at one of said plurality of locations;

designating to said mobile a voice channel to which to tune at said one of said plurality of locations in response to receiving a page response from the paged mobile;

sending information identifying the explicit location of the called and waiting mobile to the interrogation exchange via said private data lines in response to receiving an indication at said one of said plurality of locations that said mobile has tuned to the designated voice channel and is waiting on said voice channel; and

routing the call for said mobile via said PSTN communications lines from said interrogation exchange to the exchange in which said mobile station is located and waiting on a voice channel in response to receipt of information identifying the explicit location of said mobile.

5. A method for call routing as set forth in claim 4 wherein said anticipated location information is obtained from the home exchange of the called mobile station via said private data lines.

6. A method for call routing as set forth in claim 4 wherein said anticipated location information is obtained from a home location register.

7. In a telecommunications network comprising a first exchange connected to the public switched telephone network (PSTN), and a second exchange connected to a plurality of base stations having radio coverage areas in which a remote station is capable of receiving communication signals from said base stations, a method of routing communication signals from said PSTN to said remote station, said method comprising the steps of:

receiving at said first exchange a communication signal directed to said remote station;

requesting said second exchange to provide a routing number for use in routing said communication signal from said first exchange to said second exchange;

paging said remote station in at least one of said radio coverage areas;

detecting at said second exchange a page response transmitted from said remote station;

transmitting a channel assignment to said remote station after detection of said page response;

detecting at said second exchange a channel acknowlegement transmitted from said remote station;

transmitting, in response to the detection of either said page response or said channel acknowledgment, said routing number from said second exchange to said first exchange; and

routing said communication signal from said first exchange to said second exchange using said routing number.

8. The method of claim 7 wherein said communication signal received at said first exchange is a telephone call.

9. The method of claim 7 wherein said communication signal is routed through the PSTN.

10. The method of claim 7 wherein:

said telecommunications network is a cellular radio network further comprising a third exchange;

said first exchange is an interrogation exchange;

said second exchange is a visited exchange;

said third exchange is a home exchange; and

said remote station is a mobile station associated with said home exchange and being served by said visited exchange.

11. The method of claim 10 wherein said interrogation exchange requests said home exchange to provide said routing number and said home exchange, in turn, requests said visited exchange to provide said routing number.

12. A radio communications network comprising:

a mobile station;

a home exchange associated with said mobile station;

a first visited exchange having a radio coverage area in which said mobile station can roam;

an interrogation exchange connected to the public switched telephone network (PSTN);

wherein said home exchange includes;

means for identifying the exchange location of said mobile station; and

means for communicating with said visited and interrogation exchanges;

wherein said interrogation exchange includes;

means for receiving from said PSTN a call to said mobile station;

means for sending a request to said home exchange to provide a routing number for use in routing said call to said mobile station;

means for receiving said routing number from said home exchange; and

means for routing said call to said mobile station using said routing number;

wherein said first visited exchange includes;

means for receiving a request from said home exchange to provide said routing number;

means for sending a page to said mobile station upon the receipt of said routing number request from said home exchange;

means for detecting a page response from said mobile station;

means for sending a first channel designation to said mobile station upon the detection of said page response;

means for detecting a first channel confirmation from said mobile station; and

means for sending to said home exchange a first routing number corresponding to said first visited exchange upon the detection of either said page response or said first channel confirmation.

13. The network of claim 12 wherein said first visited exchange further includes means for requesting at least one other exchange to page said mobile station.

14. The network of claim 12 further comprising a second visited exchange which includes:

means for detecting said page response from said mobile station;

means for sending a second channel designation to said mobile station upon the detection of said page response;

means for detecting a second channel confirmation from said mobile station; and

means for sending to said home exchange a second routing number corresponding to said second visited exchange upon the detection of said second channel confirmation.

15. In a cellular radio network comprising a first exchange connected to the public switched telephone network (PSTN), and second and third exchanges each having a radio coverage area in which a mobile station may roam, a method for routing a call from said PSTN to said mobile station comprising the steps of:

receiving said call at said first exchange;

paging said mobile station in at least a part of said second exchange coverage area;

detecting in said third exchange coverage area a page response from said mobile station;

assigning in said third exchange coverage area a voice channel to said mobile station;

detecting in said third exchange coverage area a voice channel confirmation from said mobile station;

sending, in response to the detection of either said page response or said channel confirmation, a routing number from said third exchange to said first exchange; and

routing said call from said first exchange to said third exchange using said routing number.

16. The method of claim 15 wherein said mobile station is associated with a home exchange which maintains location information on said mobile station, and said method further comprises the step of sending a location update from said third exchange to said home exchange.

17. The method of claim 15 wherein said routing number is used to route the call through said PSTN.

18. A mobile communications system in which at least one mobile station may roam, said system comprising:

a home exchange of said at least one mobile station;

at least one visited exchange having a coverage area in which said mobile station may roam;

an interrogation exchange for receiving incoming calls for said mobile station;

private data lines connecting said home, visited and interrogation exchanges for passing signals therebetween;

PSTN communications lines connecting said interrogation and visited exchanges;

means for obtaining information as to the anticipated location of the called mobile station;

means responsive to the receipt of an incoming call for said mobile station by said interrogation exchange for paging the called mobile station in at least one of a plurality of locations based upon said anticipated location information;

means at each of said plurality of locations for receiving a page response from the paged mobile station;

means at each of said plurality of locations and responsive to receiving a page response from the paged mobile for designating to said mobile a voice channel to which to tune;

means responsive to receiving an indication at one of said plurality of locations that said mobile has tuned to a designated voice channel and is waiting on said voice channel for sending information identifying the explicit location of the called and waiting mobile to the interrogation exchange via said private data lines; and

means responsive to receipt of information identifying the explicit location of said mobile for routing the call for said mobile via said PSTN communications lines from said interrogation exchange to the exchange in which said mobile station is located and waiting on a voice channel.

19. A mobile communications system as set forth in claim 18 wherein said paging means also includes:

means for issuing a paging request to a first exchange and said first exchange is said home exchange.

20. A mobile communications system as set forth in claim 18 wherein said paging means also includes:

means for issuing a page request to a first exchange and said first exchange is a visited exchange.

21. A mobile communication system as set forth in claim 18 wherein the called mobile is paged in said plurality of different locations simultaneously.

22. A mobile communication system as set forth in claim 18 wherein the called mobile is paged in said plurality of different locations sequentially.

23. A mobile communications system as set forth in claim 18 wherein said paging means also includes:

means for issuing a page request to a first exchange; and

means within said first exchange for requesting other exchanges in an extended paging area to page the mobile.

24. A mobile communications system as set forth in claim 18 wherein said paging means also includes:

means for issuing a page request to a first exchange; and

means within said first exchange for causing said home exchange to request other exchanges in an extended paging area to page the mobile.

25. A mobile communications system as set forth in claims 23 or 24 wherein the extended paging area covers the home exchange.

26. A mobile communications system as set forth in claims 22 or 24 wherein the extended paging area covers a plurality of cooperating exchanges.