Please help me diagnose/fix this echo

Discussion in 'VOIP' started by Ramon F Herrera, Nov 8, 2005.

  1. Just when I was ready to work on the deployment of several hundred
    Asterisk SIP phones, I bumped into a serious potential show stopper: an

    I went to Astricon and attended the Echo Session. I also happen to know
    some (not a lot) about impedance matching, etc.

    My problem is mainly related to the DTMF digits when my users call an
    IVR system, from a SIP phone to a PSTN IVR.

    Would some of you folks out there (preferably knowledgeable) please
    dial into the Boston Verizon voice mail number from your SIP phone:


    and then leave a message, for instance, in my voice mail:


    (you don't have to leave anything) In fact, you will probably not be
    able to leave any message because the DTMF digits will not be

    These are my settings:

    Asterisk 1.2.0-beta2
    Sipura 2100
    Cisco AS-5300

    A colleague called from his Linksys digital hardphone and was able to
    leave me a message (i.e. the DTMF digits were recognized by Verizon),
    but then when he tried from a Sipura ATA he failed.

    It looks like it is worth purchasing the whole telephone (as opposed to
    a ATA+phone combination) if you want to prevent echo.

    I tried changing the "FXS Port Input Gain" and "FXS Port Output Gain"
    from the -3 default to -2 and -1, but no luck.


    -Ramon F Herrera
    Ramon F Herrera, Nov 8, 2005
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