I’ve got an analog phone which is currently receiving unsollicited FAX
calls from PSTN.
For learning purpose, I’m preparing an Asterisk/SPA3102 setup that would let voice calls come in and out and translate incoming FAX calls to TIF
files (forwarded through email)).
My target setup is :
PSTN <-- analog--> SPA3102 Line Port <-- SIP --> Asterisk <-- SIP -->
SPA3102 Phone Port <-- analog --> Analog phone
When a call comes in, analog phone rings. If callee answers and a fax tone is detected, then the incoming call is sent by Asterisk to ReceiveFAX application which translates incoming audio to TIF file.
My setup is working ok when I’m using ReceiveFAX in fallback mode (with f option).
Then I would like to improve my setup letting ReceiveFAX negociate T.38
with SPA3102. The trouble is SPA3102, as I configured it, seems to refuse T.38
negociation as I’m reading lines like this in Asterisk logs:
== Using UDPTL CoS mark 5
[2013-11-05 10:36:50] WARNING[C-00000007]: res_fax.c:1698
receivefax_t38_init: channel ‘SIP/myline-0000000e’ refused to negotiate T.38
My question is:
Any hint on how to configure SPA3102 PSTN Line port so that it would accept to upgrade to T.38 ?
When Asterisk re-invites SPA3102, here is the dialog between both boxes:
INVITE sip:email@example.com:5061 SIP/2.0
Via: SIP/2.0/UDP 172.16.2.1:5060;branch=z9hG4bK260a479e Max-Forwards: 70
From: <4250>;tag=as1a0daffe To: myline ;tag-2e7e5ad74dec0co1
CSeq: 102 INVITE
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH
Supported: replaces, timer X-asterisk-Info: SIP re-invite (External RTP bridge)
Content-Type: application/sdp Content-Length: 2574250>4250>
o=root 473469291 473469292 IN IP4 172.16.2.1
s=Asterisk PBX 11.5.0
c=IN IP4 172.16.2.1
m=image 4506 udptl t38