| 摘要 |
PURPOSE: A method for improving a number display error of a CNIP(Calling Number Identification Presentation) service is provided to transmit an LOCREQ(Location Request) message to a VLR while checking digit validity of a calling number within an IAM(Initial Address Message), thereby minimizing an abnormal map message. CONSTITUTION: If an originating MSC transmits an IAM to a receiving MSC(12b), a TC7(Trunk call Control for No.7) unit(12ba) of the receiving MSC(12b) checks digit validity of a calling number(S310). The TC7 unit(12ba) transmits an LOCREQ message to a VLR(12bb) of the receiving MSC(12b)(S312). The TC7 unit(12ba) is included in a traffic control subsystem of an SS-T(Switching Subsystem-Trunk), performs call processing functions, and carries out a continuity test for a speech path when necessary. The TC7 unit(12ba) retrieves digit information in a DB, adds the retrieved digit information, and relays an ISUP(ISDN User Part) signal by interfacing T17 units.
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