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Telephone compatibility

Discussion in 'Electronic Design' started by Weinberger Hans, Jan 20, 2006.

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  1. Hello ev erybody.
    Does anyone know whether the Voice dialer security system found in
    Alarm systems designed for the US is compatibile with that for Austria
    or for the rest of Europe.

  2. Ian Stirling

    Ian Stirling Guest

    Probably not.
    Dialtones and stuff vary quite widely over europe.
  3. I thought Dialer security systems were just telephones used to call
    memorized phone numbers in the alarm system.

  4. Ian Stirling

    Ian Stirling Guest

    Many may wait for a dialtone, rather than just dialing blind.
  5. Jim Thompson

    Jim Thompson Guest

    My alarm system "seizes" the line,, by hanging up (reverse the
    polarity) any active call, then dials out.

    You should see the panic that results when the maid inadvertently set
    it off... the internal horn is loud enough to hurt, then the cops
    showed up ;-)

    ...Jim Thompson
  6. So you think that one would work anywhere in the world? What model
    is your alarm?

  7. Ian Stirling

    Ian Stirling Guest

    It's gonna vary.
    Dialtones vary dramatically the world over.

    Some modem chipsets, which some alarms are going to be using to dial, check
    for dialtone.

    If you need to know, ask the manufacturer.
  8. Guest

    Alarm systems generally do not detect dialtone; they check line voltage
    to determine if the line is cut, and they have a seize relay to ensure
    that they can interrupt any call in progress. They also do not
    generally use modem chipsets (there are exceptions to both rules but
    mass-market appliances tend to use simple DTMF generators/recognizers).
    The system decides if communications startup was successful by waiting
    for a handshake tone from the central station, and a kissoff tone after
    the report session is finished.

    Audio verification systems start by sending a DTMF report in the method
    described, then flag the central station to switch the call through to
    an operator after kissoff rather than just hanging up.

    Sometimes there are special regulatory rules that require the alarm
    system to monitor and recognize PSTN-provided call progress tones, but
    this is not the norm.
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