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Number portability using ISUP message option

  • US 5,610,977 A
  • Filed: 12/27/1995
  • Issued: 03/11/1997
  • Est. Priority Date: 12/21/1995
  • Status: Expired due to Term
First Claim
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1. In a telephone network having a number of telephone switching offices equipped with SSPs (Service Switching Points) operating with IN (Intelligent Network) application software, and a remotely located SCP (Service Control Point) adapted to receive, when required, SS7 (Signalling System 7) messages from the SSPs to translate a dialled number to enable the routing of call on the telephone network, a method of providing number portability for the treatment of calls from a calling party to a specific number of a called party, comprising the steps of:

  • a) receiving digits dialled by said calling party at an exchange serving said calling party;

    b) establishing a call path from said exchange serving said calling party to a terminating office associated with the dialled digits;

    c) receiving an Initial Address Message (IAM) at said terminating office and determining whether said call is directed to a portable number;

    d) launching a query to a database, if said call is directed to a portable number to obtain a routing option to enable said call to be routed to said called party;

    e) creating at said terminating office, a modified Integrated Services Digital Network (ISDN) User Part (ISUP) message containing an indication that the called party number is a portable number and incorporating a new routing option, if said call is directed to a portable number;

    f) determining whether an intermediate switching office along the signalling path is capable of supporting number portability, if said exchange serving said calling party is unable to support number portability;

    g) sending said modified ISUP message from said terminating office to said intermediate switching office along said call path, if said exchange is unable to service the call;

    h) receiving said routing option at said intermediate switching office; and

    i) creating a new IAM to enable the call to reach the called party.

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