[asterisk-users] How to enable T.38 between SPA3102 PSTN Line port and ReceiveFAX app ?

[Olivier]

Hello,

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[3061][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:myline at 172.16.2.12:5061 SIP/2.0
Via: SIP/2.0/UDP 172.16.2.1:5060;branch=z9hG4bK260a479e
Max-Forwards: 70
From: <sip:4250 at 172.16.2.1>;tag=as1a0daffe
To: myline <sip:myline at 172.16.2.1>;tag=2d2e7e5ad74dec0co1
Contact: <sip:4250 at 172.16.2.1:5060>
Call-ID: c8278ef2-b80a5454 at 172.16.2.12
CSeq: 102 INVITE
User-Agent: FPBX-2.11.0(11.3.0)
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: 257

v=0
o=root 473469291 473469292 IN IP4 172.16.2.1
s=Asterisk PBX 11.5.0
c=IN IP4 172.16.2.1
t=0 0
m=image 4506 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxDatagram:849
a=T38FaxUdpEC:t38UDPFEC

---

<--- SIP read from UDP:172.16.2.12:5061 --->
SIP/2.0 488 Not Acceptable Here
To: myline <sip:myline at 172.16.2.1>;tag=2d2e7e5ad74dec0co1
From: <sip:4250 at 172.16.2.1>;tag=as1a0daffe
Call-ID: c8278ef2-b80a5454 at 172.16.2.12
CSeq: 102 INVITE
Via: SIP/2.0/UDP 172.16.2.1:5060;branch=z9hG4bK260a479e
Contact: myline <sip:myline at 172.16.2.12:5061>
Warning: 304 spa "Media type not available"
Server: Linksys/SPA3102-5.1.10(GW)
Content-Length: 0



Any hint ?

Regards
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