[asterisk-users] T.38 - By reinvitation only?

[Alex Lake]

Notwithstanding that lot above, I would like to try T.38 but it didn't 
quite work the way I was hoping.

I've got calls coming in on a context "gamma" and am sending them out on 
a context "gamma-OUT". I've put the following into each SIP peer definition:

canreinvite     = yes
t38pt_udptl     = yes

However, when I place a call to a fax machine, I get the following message:
WARNING[13698]: chan_sip.c:4691 process_sdp: Unsupported SDP media type 
in offer: image 28326 udptl t38

The full exchange is shown below.

Thanks for any light anyone can shed on this!
Rgds,
Alex

PS - Let me know if there's a better way to put all this stuff in a posting.

-------------------

INVITE sip:442070173460 at 89.202.128.200 SIP/2.0

Max-Forwards: 69

Session-Expires: 3600;Refresher=uac

Supported: timer

To: "442070173460" <sip:442070173460 at 89.202.128.200>;tag=as0cfcd0f2

From: <sip:442070600003 at 83.245.6.83>;tag=3373030299-438089

Call-ID: 2b91c1ee563365b54ae5d9ad53df4855 at 89.202.128.200

CSeq: 2 INVITE

Via: SIP/2.0/UDP 
83.245.6.83:5060;branch=z9hG4bK58ebba15bca29d9c48091635d0a0f023

Contact: sip:442070600003 at 83.245.6.83:5060

Allow-Events: telephone-event

Content-Type: application/sdp

Content-Length: 344

 

v=0

o=msw 4535 11 IN IP4 83.245.6.83

s=sip call

c=IN IP4 83.245.6.84

t=0 0

m=image 28326 udptl t38

a=T38FaxUdpEC:t38UDPRedundancy

a=T38FaxMaxDatagram:72

a=T38FaxMaxBuffer:200

a=T38FaxRateManagement:transferredTCF

a=T38FaxTranscodingJBIG:0

a=T38FaxTranscodingMMR:0

a=T38FaxFillBitRemoval:0

a=T38MaxBitRate:14400

a=T38FaxVersion:0

 

<------------->

--- (13 headers 15 lines) ---

Sending to 83.245.6.83 : 5060 (no NAT)

[Nov 20 16:51:40] WARNING[13698]: chan_sip.c:4691 process_sdp: 
Unsupported SDP media type in offer: image 28326 udptl t38

 

<--- Transmitting (no NAT) to 83.245.6.83:5060 --->

SIP/2.0 488 Not acceptable here....