Incoming FAX over SIP

Asterisk Asterisk Support
1

I know I have raised thsi before without success… This is really getting to me!

I am trying to receive FAX over a SIP connection. I am using
NVFaxDetect as described in
voip-info.org/wiki-NVFaxDetect

What happens is that the function says it recognises a FAX but then says there is nbo fax extension; but there is

Dialplan sections where FAX is mentioned

[ Context ‘vfax’ created by ‘pbx_config’ ]
‘300’ => 1. ringing()
2. wait(3)
3. Answer()
4. AbsoluteTimeout(35)
5. SetVar(FAXFILE=/var/spool/asterisk/fax/${UNIQUEID}.tif)
6. rxfax(${FAXFILE}|debug)
‘T’ => 1. Hangup()
‘h’ => 1. system(echo Fax from ${CALLERIDNUM} in ${FAXFILE} | /usr/bin/mail -s incoming-Fax jpff)
‘s’ => 1.SetVar(FAXFILE=/var/spool/asterisk/fax/${UNIQUEID}.tif)
2. rxfax(${FAXFILE}|debug)

[ Context ‘incoming’ created by ‘pbx_config’ ]
‘7625624’ =>1. Wait(3)
2. Answer()
3. Playtones(ring)
4. NVFaxDetect(10|dt)
5. StopPlaytones()
6. Playback(codemist_ltd)
7. Playback(noFax)
8. Hangup()
‘fax’ => 1. goto(vfax|s|1)
2. Hangup()
‘s’ => 1. Wait(3)
2. Answer()
3. NVBackgroundDetect(codemist_ltd)
4. Dial(SIP/jpff-phone&SIP/lap-phone&SIP/aff-phone|20|tr)
5. VoiceMail(u9999)
6. Hangup()
105. VoiceMail(b9999)
106. Hangup()

Calls are from Sipgate.co.uk and the fax line is 7625624

System is Debian, asterisk from apt-get with NV plugins

2

post a log file fragment for a failed fax call.

3

The last failure said (in /var/log/asterisk/messages)

2006-11-20 12:50:47 NOTICE[30288]: Redirecting SIP/gw02.uk.sipgate.net-41ad7220
to fax extension
2006-11-20 12:50:47 WARNING[30288]: Context
2006-11-20 12:50:47 WARNING[30288]: Fax detected, but no fax extension
2006-11-20 12:50:47 NOTICE[30288]: Dropping incompatible voice frame on SIP/gw02
.uk.sipgate.net-41ad7220 of format slin since our native format has changed to a
law

4

ok, then can you post your exact extensions.conf entry for the incoming context where this call is rec’d, and not the “flow” as you’ve posted in the OP ?

5

From sip.conf

[sipgate-in]
; For incoming calls only.
type=user
context=incoming

From extensions.conf

[incoming]
exten => s,1,Wait(3)
exten => s,2,Answer()
exten => s,3,NVBackgroundDetect(codemist_ltd)
exten => s,4,Dial(SIP/jpff-phone&SIP/lap-phone&SIP/aff-phone,20,tr)
exten => s,5,VoiceMail,u9999
exten => s,105,VoiceMail,b9999
exten => s,6,Hangup()
exten => s,106,Hangup()

…
;; FAX line from sipgate (Bath 808173)
exten => fax,1,goto(vfax,s,1)
exten => fax,2,Hangup

exten => 7625624,1,Wait(3)
exten => 7625624,2,Answer
exten => 7625624,3,Playtones(ring)
exten => 7625624,4,NVFaxDetect(10|dt)
exten => 7625624,5,StopPlaytones
exten => 7625624,6,Playback(codemist_ltd)
exten => 7625624,7,Playback(noFax)
exten => 7625624,8,Hangup

[vfax]

exten => s,1,SetVar(FAXFILE=/var/spool/asterisk/fax/${UNIQUEID}.tif)
exten => s,2,rxfax(${FAXFILE}|debug)

(That omits two other incoming lines that are voice lines)

Is that the right information?

6

Hate to be a debbie downer, but im completely convinced Fax on asterisk is a half-truth at best. Fax over VoIP was a 5 month train-wreck for me. your best luck is to receive faxes thru pri using spanDSP, and email them or store them on a share (per user basis.) yet even this didnt work 100% for me (card timing issues at the PRI.) I went with E-Fax and cut my losses.

if you do find a solution, I would be grateful to hear, but fax and voip have a well documented history of incompatibility.

7

I have struggled with faxing for a very long time. Sometimes it works and sometimes it doesn’t. we have tried many different hardware platforms and many different configurations. We no longer offer fax support with our product - we just install a phone line from the ILEC and we’re done with it. As the poster above says, we have cut our losses.