Fax Detect On Demand

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Asterisk Users 4 Comments

Using Asterisk 1.8.mumble. We would like to use fax detect on demand.

Both chan_dahdi and chan_sip support setting fax detetect on a static basis, but no way I’ve been able to find to enable/disable it on demand in the dialplan.

In 1.4 we used the NVFaxDetect 3rd party app, but that no longer appears to be maintained.

Does anyone have any suggestions?

4 thoughts on - Fax Detect On Demand

  • 2012/8/16 Eric Wieling

    For curiosity’s sake, could you make it work first using static settings ?

    but no way I’ve been able to find to enable/disable it on demand in the

  • Yes. Trivial

    Off the top of my head:

    exten => 12125551212,1,Set(EMAIL=john.doe@example.com)
    exten => 12125551212,n,Answer exten => 12125551212,n,Wait(4)
    exten => 12125551212,n,Dial(SIP/1212)

    exten => fax,1,ReceiveFax(/tmp/myfax.tiff)
    exten => fax,n,AGI(yourfax2emailagi.php,${FAXEXTEN},${EMAIL})

    The Answer and Wait are required for faxdetection to work.

    —–Original Message—

  • 2012/9/13 Eric Wieling

    It doesn’t work for me : using your example, SIP phone 1212 user would pick its handset up when it starts to ring, he would hear CNG tone but nothing happens and dialplan’s fax extension is not entered. In my setup, I used a fax machine connected to an Asterisk FXS port. This machine dialed the SIP phone.

    I also used SendFAX application with the very same SIP phone and it did work the same way: callee could hear fax tone and branching to fax extension didn’t happen. Nothing in CLI showed fax tone recognition.

    In your setup, which type of incoming channel was calling the extension
    121255551212 ?

    You did set SIP1212 faxdetect to yes, didn’t you ?
    Did you enter any value sup t38p_udptl parameter ?

    As a side note, if I tweak FXS port setting to detect fax, it works.

  • No. While the Wait(4) is waiting Asterisk should detect the fax tone of the sending fax machine and the call should be sent to the fax extension and never ring the phone.

    Fax detect must be configured on the INCOMING channel. In my case that is DAHDI.

    —–Original Message—