Does anyone have any reliable configurations for faxing using a Mediant 1000? We are having a ton of issues lately. We are using T38 Relay on the unit, the baud rate has already been lowered to 14.4 on the gateway as well as the machines themselves (Canon MFD units). It seems to be a negotiation issue as looking through the call traces after the DETECT_FAX we are getting BYE. Also some calls last like 30 secs and then disconnect? Any ideas?

  • kryo2019B
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    10 months ago

    Man voip and fax are like oil and water. If you can get them to mix one way or the other, they’re fine. Otherwise you just end up with an oil slick in your pond.

    I don’t know how many times I’ve fought with ATA’s, clients, up stream, our own NOC with faxing issues. The only one I never had issues with as a plain old analog line.

    Does your carrier officially support T38? Or do they say the same as everyone else “Best Effort”™?

    Are you able to listen to the pcaps at all and hear if anything sounds off? … I guess that would only work on g.711 calls, not t38.

    There was a fax decoder I had found eons ago, ran it through cmd prompt, and it would spit out a readable log file that shows all the fax handshakes, etc. But I a) lost the download when my last laptop died, and b) cannot for the life of me find it again online.

    Are you able to force the codec to be just g711 and see if the fax machine has issues still? It’s not impossible that the fax just isn’t working properly.