fax confusion

Discussion in '3CX Phone System - General' started by smokeman, Dec 5, 2011.

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  1. smokeman

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    alright, so I'm totally confused on faxing. We made sure our provider supports t.38(nexvortex), and we purchased patton m-ata analog gateway devices, which support t.38. I've set up a fax machine, with a modem rate of 9600, as I've read several places to do with fax on a voip system. I can fax from extension, to extension internally, however I can not get faxing to work to an outside fax number.
    I did find the wiki that had definitions for the patton m-ata:
    https://sites.google.com/a/3cx.com/3cx-wiki/phone-configuration/vendor-supported/patton-m-ata

    my confusion is from what type of extension to set up for this...
    I've tried adding a fax extension, and using that info to put into the patton m-ata(thinking maybe you had to do it that way),
    I've tried a regular extension(which doesn't allow for any codec settings, beyond pbx delivers audio)
    I've tried using a patton pstn definition, and forcing it to 1 port(of which I then put the sip extension login information in the patton)
    I get the patton to register with all these methods, however faxes won't go through.
    on the pstn definition, the fax tries to send to the operator extension, maybe I'm missing an outbound rule...I just can't find any tutorials for faxing beyond the what is foip, and a few forum posts.

    the patton m-ata's fall back to g711, which nexvortex supports.
    I can't get the patton mata to log to our syslog server, which would help to have errors.

    any tips/advice from the community/3cx?
    thanks,
    Barry Smoke
    AR Legislative Audit
     
  2. eagle2

    eagle2 Well-Known Member

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    Fax over IP is something not so easy to make running.
    Regarding your provider Nexvortex search the forum -- I think I met some comments about faxing with them.

    Generally what you can do with 3CX faxing is the following:

    (1) receive faxes by 3CX fax server (default extension 888) and send them as e-mail (.pdf attachment); this works only with T.38 providers

    (2) send and receive faxes using VoIP adapter supporting T.38 (and fax machine) -- this is working for me successfully with SPA-3102, no reason for not working with other brands; the important thing is the fax extension must be defined as such, T.38 will NOT work with regular 3CX extensions, regardless of the VoIP adapter; this will also not work if the provider is not supporting T.38 and the adapter is not allowing G.711 passthrough

    (3) send and receive faxes using VoIP adapter NOT supporting T.38, in this case is obligatory to force using of PCM codec only, i.e. G.711a/µ; you may use regular 3CX extensions also for the purpose; however success rate is less than 50% usually

    T.38 faxing is sensitive to network delays, jitters, etc. For SPA-3102 there is a special setup recommendation for using as fax. I assume there are similar recommendations in your case (for your adapter) like the link you posted. The VoIP adapter must be located close to the 3CX server (ping ≤ 1ms) in the same LAN segment (no routing or NAT).

    Regards
     
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  3. smokeman

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    that is good to know, on the extension must be defined as a fax extension. This is contrary to what a local vendor just told me. He was trying to force g711u through the mata, and even had disable t.38 checked.
     
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