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telephone monitoring circuitry

Discussion in 'Electronic Basics' started by Will Barbour, Apr 8, 2007.

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  1. Will Barbour

    Will Barbour Guest


    This seems to be an active newsgroup and so I was wondering if there is
    someone who could help me with a techie problem...

    I am developing hardware/software to monitor the performance of a small
    call centre (~5 phones).

    On a daily basis I need to retrieve statistics such as the amount of
    time the phones are in use, are on hold, how many calls are received, etc.

    To this aim, i will need to periodically poll the status of each of the
    phones (from a PC). Status being either:

    * Not in use
    * Ringing
    * On hold
    * In conversation

    So I was thinking that I could have a device which would sit in between
    the phones and the junction box,and make the status(es) available to a
    PC via a serial port.

    The device would act as a finite state machine,moving from state to
    state when a RING, DIALTONE or SPEECH (or lack of) is detected. The
    status could be made available via the use of a couple of pins on a
    serial port.

    As I am not overly experienced either with electronics, or telephone
    protocols, I was wondering if anybody knows of how this device could be
    built. Or any fresh ideas as to how I could achieve the same aim??

    Many thanks

  2. jasen

    jasen Guest

    why not get that data from your PABX

  3. Will Barbour

    Will Barbour Guest

    I do not have access to this.

  4. Ross Herbert

    Ross Herbert Guest

    Solving the problems will require schematic details of the system you
    want to monitor. Small 5 line switching systems don't necessarily
    conform to the same standards as a CO or PSTN exchange.

    Most monitoring systems used to gather this type of data don't sit in
    between the system and the phone, they simply sit across the line as a
    relatively high impedance device. Voltage levels will give data as to
    the actual state of the line (on-hook, off-hook, ringing, line lockout
    - eg, one party may have hung up but the other remains off-hook).
    Speech is not usually monitored due to privacy concerns and there is
    hardly much point to detecting whether somebody is actually speaking
    or not. It is usual to "assume" that if a phone is off-hook and not
    ringing, that two way conversation is taking place. Where a phone
    remains off-hook for extended periods without having dialled there may
    be a tone and/or voltage level change to indicate this condition.
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