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Fax Server not answering

Discussion in '3CX Phone System - General' started by jwoodland, Jun 19, 2015.

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  1. jwoodland

    May 22, 2014
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    We are on 3CX Enterprise version 12 service pack 6.2.

    When we first implemented version 12 in September 2014, I had tested the Fax server with no issues.

    Now I am trying to set up a DID to fax to email and it just hangs up immediately. The same DID will work fine if sent to an extension, so I know the DID is working.

    Our voip provider is ThinkTel, and we have physical fax machines working over Voip through Patton Gateways with no issue.

    Any reason why the Fax service would be rejecting the call? Things to check?

    No errors in the logs and I have restarted the Fax service several times and the entire 3CX services once.

  2. pj3cx

    pj3cx Active Member

    Aug 1, 2013
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    Hi there,
    In order to receive faxes through our fax server you will need to ensure that your voip provider supports T38. Audio faxes are not supported.
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  3. jwoodland

    May 22, 2014
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    I was previously able to receive faxes, so I know that T.38 is supported.

    Anyone have an idea why the system would just drop the call after one second, before a fax tone or anything happens?

    Here is the activity log from my test call:

    19-Jun-2015 13:40:13.182 [MS105000] C:774.2: No RTP packets were received:remoteAddr=,extAddr=,localAddr=
    19-Jun-2015 13:40:12.321 Leg L:774.2[Fax] is terminated: Cause: BYE from PBX
    19-Jun-2015 13:40:12.321 [CM503008]: Call(C:774): Call is terminated
    19-Jun-2015 13:40:12.320 Leg L:774.1[Line:10002<<2505898663] is terminated: Cause: BYE from PBX
    19-Jun-2015 13:40:10.667 [CM503007]: Call(C:774): Fax:8888 has joined, contact <sip:8888@>
    19-Jun-2015 13:40:10.666 [CM503007]: Call(C:774): Line:10002<<2505898663 has joined, contact <sip:7787473998@>
    19-Jun-2015 13:40:10.665 L:774.2[Fax] has joined to L:774.1[Line:10002<<2505898663]
    19-Jun-2015 13:40:10.645 [CM503025]: Call(C:774): Calling T:Fax:8888@[Dev:sip:8888@;user=phone] for L:774.1[Line:10002<<2505898663]
    19-Jun-2015 13:40:10.636 [CM503027]: Call(C:774): From: Line:10002<<2505898663 ("Tax Certificates Fax:JON WOODLAND" <sip:2505898663@>) to T:Fax:8888@[Dev:sip:8888@;user=phone]
    19-Jun-2015 13:40:10.636 [CM503004]: Call(C:774): Route 1: from L:774.1[Line:10002<<2505898663] to T:Fax:8888@[Dev:sip:8888@;user=phone]
  4. lneblett

    lneblett Well-Known Member

    Sep 7, 2010
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    You did not mention how the DID is coming arriving at the system. Is it a direct connection from the SIP provider or is it coming in from the Patton you mentioned. The reason the call dropped is that it did not see any RTP packets.

    Do it again and use the verbose mode when looking at the call. Ideally, you will see more of how the devices are negotiating and then connecting to one another. You should see something like:
    o=3CXFaxServer 2890844526 890844528 IN IP4 netbricks.com
    c=IN IP4
    t=0 0
    m=image 10000 udptl t38

    This is a sample of a fax call I just sent to my office. As you can see, t38 is in the equation. This is on a DID coming in to the system directly.
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