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Handoff procedure that minimizes disturbances to DTMF signalling in a cellular radio system

  • US 5,140,627 A
  • Filed: 10/09/1990
  • Issued: 08/18/1992
  • Est. Priority Date: 10/09/1990
  • Status: Expired due to Term
First Claim
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1. A cellular mobile radiotelephone communication system, comprising:

  • mobile radiotelephone means for sending DTMF messages over an air interface;

    first and second base station means for converting the DTMF messages into DTMF tones and transmitting the DTMF tones;

    switching controller means, connected to the first and second base station means, including means for receiving the DTMF tones and means for ordering a handoff of the mobile means from the first base station to the second base station, wherein some DTMF tones remain untransmitted;

    means for transferring untransmitted DTMF information from the first base station to the second base station sot hat both the first and second base stations transmit the untransmitted DTMF tones to the mobile station for a predetermined time; and

    means for terminating transmission of the untransmitted DTMF tones from the first base station after the predetermined time expires.

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