fax relay over IP - G.711, T.38

Discussion in 'VOIP' started by Sani Rus, Feb 23, 2006.

  1. Sani Rus

    Sani Rus Guest

    Hello group!

    I wish to exchange experiences with someone who managed to successfully and
    reliably set up the fax relay over the IP - either running G.711 or T.38 on
    the IP side. Of special interest for me are the configurable parameters
    which influences the reliability of the transmission - both parameters on
    the gateways and on the faxes.

    Network topology is as follows:

    analog fax A - access GW - IP network - trunking GW - TDM network - trunking
    GW - IP network - access GW - analog fax B

    Does it make sense to run T.38 in such configuration (4 GW conversion
    involved)? Is T.38 more suitable for 2 GW conversion only?

    In general - how do standard analog faxes (e.g. Cannon, Brother, Panasonic)
    or analog fax modems (e.g. US Robotics, Zyxel) perform in an IP network? Can
    we configure them in any way to make them aware of the IP network? Any
    comment or experience is more than welcome.

    Best regards,


    rus(no spam)@iskratel.si

    ommit (no spam) from e-mail address
    Sani Rus, Feb 23, 2006
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  2. Sani Rus

    carcarx Guest

    I'm using a VoIP provider that runs a G.711 codec by default. I can't
    tell you
    what their network backbone uses, for certain, other than to say I know
    its an IP
    backhaul from the Sipura SPA-2100 in my house to their IP POP.

    Our fax machine is a 1994 era Brother. The fax transmission looks
    "clean" on the
    receiving side, but we believe we have seen a packet drop.

    The status indication on our fax machine indicates "line condition
    problems", and when
    we hear the modem interaction there appears to be a bunch of white
    noise on the line,
    upon fax transmission initiation.

    We could use "overseas mode" on that old fax machine should we
    encounter problems.
    carcarx, Feb 24, 2006
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