[asterisk-users] Problem with detecting fax on PRI/DAHDI channels

[Kevin P. Fleming]

On 06/23/2011 09:12 AM, Sawan Vithlani wrote:
> Hello all,
>
> I am using  call files to dial out to a set of PSTN numbers. The calls
> are going out fine and being handled correctly by the dial plan.
>
> The problem occurs when I accidentally call a fax machine. I would
> expect the dial plan to pick this up and jump to the "fax" extension
> in the current context. This is not happening.
>
> In the call file I send the call out via Dial(DAHDI/g0/XXXXXXXX) and
> then it goes to my dial plan context:
>
> [SendCall]
> exten =>  start,1,Answer()
>     same =>  n, Wait(5)
>     same =>  n, ..... ;; do some more stuff
>
> exten =>  fax,1,Verbose(got a Fax on ${EXTEN})
> same =>n, Hangup()
>
> ;;;;
>
>   I do get a message on the CLI telling me "Channel 63 detected a CED
> tone from the network" but still no jumping to the fax extension.
> This is while dialplan is in the Wait(5).
>
> CLI>  core show version
> Asterisk 1.8.4.1-1digium1~natty built by pbuilder @ nighthawk on a
> x86_64 running Linux on 2011-05-23 22:05:17 UTC
>
> ISDN lines connected via Digium TE412P card.
>
> I have "faxdetect = both" in chan_dahdi.conf in the general section as
> well as specifically for the configured spans.

'faxdetect' is for detecting *calling* FAX machines, not *called* FAX 
machines. It listens for the CNG tone generated by a (non-V.34) calling 
FAX terminal.

If you are wanting to detect that a number you have dialed is being 
answered by a FAX machine, there are applications available (but not 
included with Asterisk) to do that. I believe NVFaxDetect can do it, and 
most of the add-on answering machine detection applications can do it as 
well.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at www.digium.com & www.asterisk.org