Method for conducting handoff back to anchor communication scenarios

• US 6,577,867 B1
• Filed: 03/31/2000
• Issued: 06/10/2003
• Est. Priority Date: 03/31/2000
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Elizondo, Alejandro A.
• Primary Examiner(s): MAUNG, NAY AUNG
• Application Number:
  US09/540,073
• Time in Patent Office: 1,166 Days
• Field of Search: 455/405, 455/406, 455/422, 455/432, 455/433, 455/436, 455/438, 455/439, 455/449, 455/445, 455/560, 455/561, 379/115.01, 379/115.03, 379/121.04, 379/121.05, 379/127.03, 379/127.06, 379/211.02
• US Class Current: 455/436
• CPC Class Codes: H04W 36/12 Reselecting a serving backbone network switching or routing node

Abstract

A method which supports Mobile Station (MS) handoff back operations across tandem switches makes use of a modification to the ANSI-41 Standard. The method includes the steps of determining that a handoff back call connection operation to a Target Mobile Switching Center (involved in the call path and not directly connected to the Serving Mobile Switching Center) should occur, verifying that the Target Mobile Switching Center (Target MSC) is also the Anchor MSC, verifying that a designated channel of the Target MSC is available to support the MS, and moving the MS directly to the designated channel. The address of the Anchor MSC is obtained using the MSCID contained within the BillingID parameter of a FacilitiesDirective message received by the tandem MSC directly connected to the serving MSC prior to initiating the handoff back operation. The method operates within a telecommunications network, including an MS served by a Serving MSC connected along a call path to one or more Tandem MSCs and the AMSC, and which is connected in series with the Tandem MSCs by one or more inter-MSC trunks. The handoff back call connection operation occurs directly from the SMSC to the AMSC and may even be used within networks which do not support path minimization operations.

Claims

1. A method supporting a handoff back call connection operation within a telecommunications network including a Mobile Station (MS) served by a Serving Mobile Switching Center (SMSC) connected along a call path to a Tandem MSC (TMSC) and an Anchor Mobile Switching Center (AMSC), wherein the AMSC is connected to the TMSC by a first inter-MSC trunk and the TMSC is connected to the SMSC by a second inter-MSC trunk, wherein the AMSC includes a designated channel, and wherein the handoff back call connection operation occurs from the SMSC to the AMSC, comprising the steps of:

receiving at the SMSC a message including a BillingID parameter containing an identification number for the AMSC;

determining by the SMSC that the handoff back call connection operation to a Target MSC should occur;

determining from the identification number for the AMSC that the target MSC is the AMSC;

verifying that the designated channel of the AMSC is available to support the MS; and

moving the MS to the designated channel of the MSC by using a handoff back command addressed to the identification number for the AMSC.

2. The method of claim 1, wherein the step of determining from the identification number for the AMSC that the Target MSC is the AMSC includes the steps of:

obtaining an identification number for the Target MSC; and

comparing the identification number for the AMSC with the identification number for the Target MSC.

3. The method of claim 1, wherein the step of verifying that the designated channel of the AMSC is available to support the MS includes the steps of:

sending a Handoff Back message from the SMSC to the AMSC to direct the AMSC to initiate an intersystem handoff task; and

sending a Handoff Back response from the AMSC to the SMSC to verify the designated channel is available to support the MS.

4. The method of claim 1, wherein the step of moving the MS to the designated channel of the MSC includes the steps of:

sending a MobileHandoffOrder message from the SMSC to the MS;

receiving by the AMSC of the MS on the designated channel; and

sending a Mobile Station On Channel message from the AMSC to the SMSC.

5. The method of claim 1, including the step of:

sending a message along the call path from the AMSC to the TMSC and the SMSC directing the TMSC and the SMSC to release the first and second inter-MSC trunks.

6. The method of claim 5, wherein the step of sending a message along the call path from the AMSC to the TMSC and the SMSC directing the TMSC and SMSC to release the first and second inter-MSC trunks includes the steps of:

sending a FacilitiesRelease message along the call path from the AMSC to the TMSC;

sending a FacilitiesRelease message along the call path from the TMSC to the SMSC;

sending a FacilitiesRelease response along the call path from the SMSC to the TMSC; and

sending a FacilitiesRelease response along the call path from the TMSC to the AMSC.

7. A method supporting a handoff back call connection operation within a telecommunications network including a Mobile Station (MS) served by a Serving Mobile Switching Center (SMSC) connected along a call path to a Tandem MSC (TMSC) and an Anchor Mobile Switching Center (AMSC), wherein the AMSC is connected to the TMSC by a first inter-MSC trunk and the TMSC is connected to the SMSC by a second inter-MSC trunk, wherein the AMSC includes a designated channel, and wherein the handoff back call connection operation occurs from the SMSC directly to the AMSC, comprising the steps of:

receiving at the SMSC a message including a BillingID parameter containing an identification number for the AMSC;

determining by the SMSC that the handoff back call connection operation to a Target MSC should occur,

determining from the identification number for the AMSC that the Target MSC is the AMSC;

verifying that the designated channel of the AMSC is available to support the MS;

moving the MS directly to the designated channel of the AMSC; and

directing the TMSC and SMSC to release the first and second inter-MSC trunks.

8. The method of claim 7, wherein the step of determining from the identification number for the AMSC that the Target MSC is the AMSC includes the steps of:

obtaining an identification for the Target MSC; and

comparing the identification number for the AMSC with the identification number for the Target MSC.

9. The method of claim 7, wherein the step of verifying that the designated channel of the AMSC is available to support the MS includes the steps of:

sending a Handoff Back message from the SMSC to the AMSC to direct the MSC to initiate an intersystem handoff task; and

sending a Handoff Back response from the AMSC to the SMSC to verify the designated channel is available to support the MS.

10. The method of claim 7, wherein the step of moving the MS to the designated channel of the AMSC includes the steps of:

sending a Mobile Handoff Order message from the SMSC to the MS;

receiving the MS on the designated channel; and

sending a Mobile Station On Channel message from the AMSC to the SMSC.

11. The method of claim 7, wherein the step of directing the TMSC and SMSC to release the first and second inter-MSC trunks includes the steps of:

sending a Facilities Release message along the call path from the AMSC to the TMSC;

sending a Facilities Release message along the call path from the TMSC to the SMSC;

sending a FacilitiesRelease response along the call path from the SMSC to the TMSC; and

sending a Facilities Release response along the call path from the TMSC to the AMSC.

12. A method supporting a handoff back call connection operation within a telecommunications network including a Mobile Station (MS) served by a Serving Mobile Switching Center (SMSC) connected along a call path to a Tandem MSC (TMSC) and an Anchor Mobile Switching Center (AMSC) which is unable to support path minimization, wherein the AMSC is connected to the TMSC by a first inter-MSC trunk and the TMSC is connected to the SMSC by a second inter-MSC trunk, wherein the AMSC includes a designated channel, and wherein the handoff back call connection operation occurs from the SMSC to the AMSC, comprising the steps of:

receiving at the SMSC a message including BillingID parameter containing an identification number for the AMSC;

determining by the SMSC that the handoff back call connection operation to a Target MSC should occur;

determining from the identification number for the AMSC that the Target MSC is the AMSC;

verifying that the designated channel of the AMSC is available to support the MS; and

moving the MS to the designated channel of the MSC by using a handoff back command addressed to the identification number for the AMSC.

13. The method of claim 12, wherein the step of determining from the identification number for the AMSC that the Target MSC is the AMSC includes the steps of:

obtaining an identification number for the Target MSC; and

comparing the identification number for the AMSC with the identification number for the Target MSC.

14. The method of claim 12, wherein the step of verifying that the designated channel of the AMSC is available to support the MS includes the steps of:

sending a Handoff Back message from the SMSC to the AMSC to direct the AMSC to initiate an intersystem handoff task; and

sending a Handoff Back response from the AMSC to the SMSC to verify the designated channel is available to support the MS.

15. The method of claim 12, wherein the step of moving the MS to the designated channel of the MSC includes the steps of:

sending a MobileHandoffOrder message from the SMSC to the MS;

receiving by the AMSC of the MS on the designated channel; and

sending a Mobile Station On Channel message from the AMSC to the SMSC.

16. The method of claim 12, including the step of:

sending a message along the call path from the AMSC to the TMSC and the SMSC directing the TMSC and the SMSC to release the first and second inter-MSC trunks.

17. The method of claim 16, wherein the step of sending a message along the call path from the AMSC to the TMSC and the SMSC directing the TMSC and SMSC to release the first and second inter-MSC trunks includes the steps of:

sending a FacilitiesRelease message along the call path from the AMSC to the TMSC;

sending a FacilitiesRelease message along the call path from the TMSC to the SMSC;

sending a FacilitiesRelease response along the call path from the SMSC to the TMSC; and

sending a FacilitiesRelease response along the call path from the TMSC to the AMSC.

18. A method supporting a handoff back call connection operation within a telecommunications network including a Mobile Station (MS) served by a Serving Mobile Switching Center (SMSC) connected along a call path to a Tandem MSC (TMSC) which is unable to accept a HandoffToThird message for execution, and an Anchor Mobile Switching Center (AMSC), wherein the AMSC is connected to the TMSC by a first inter-MSC trunk and the TMSC is connected to the SMSC by a second inter-MSC trunk, wherein the AMSC includes a designated channel, and wherein the handoff back call connection operation occurs from the SMSC to the AMSC, comprising the steps of:

receiving at the SMSC a message including a BillingID parameter message containing an identification number for the AMSC;

determining by the SMSC that the handoff back call connection operation to a Target MSC should occur;

determining from the identification number for the AMSC that the Target MSC is the AMSC;

verifying that the designated channel of the AMSC is available to support the MS; and

moving the MS to the designated channel of the MSC by using a handoff back command addressed to the identification number for the AMSC.

19. The method of claim 18, wherein the step of determining from the identification number for the AMSC that the Target MSC is the AMSC includes the steps of:

obtaining an identification number for the TargetMSC; and

comparing the identification number for the AMSC with the identification number for the Target MSC.

20. The method of claim 18, wherein the step of verifying that the designated channel of the AMSC is available to support the MS includes the steps of:

sending a Handoff Back message from the SMSC to the AMSC to direct the AMSC to initiate an intersystem handoff task; and

sending a Handoff Back response from the AMSC to the SMSC to verify the designated channel is available to support the MS.

21. The method of claim 18, wherein the step of moving the MS to the designated channel of the MSC includes the steps of:

sending a MobileHandoffOrder message from the SMSC to the MS;

receiving by the AMSC of the MS on the designated channel; and

sending a Mobile Station On Channel message from the AMSC to the SMSC.

22. The method of claim 18, including the step of:

sending a message along the call path from the AMSC to the TMSC and the SMSC directing the TMSC and the SMSC to release the first and second inter-MSC trunks.

23. The method of claim 22, wherein the step of sending a message along the call path from the AMSC to the TMSC and the SMSC directing the TMSC and SMSC to release the first and second inter-MSC trunks includes the steps of:

sending a FacilitiesRelease message along the call path from the AMSC to the TMSC;

sending a FacilitiesRelease message along the call path from the TMSC to the SMSC;

sending a FacilitiesRelease response along the call path from the SMSC to the TMSC; and

sending a FacilitiesRelease response along the call path from the TMSC to the AMSC.