[asterisk-users] sending T.38 fax negotiation problem

[Kevin P. Fleming]

On 05/03/2010 11:59 AM, Ilmars Knipshis wrote:

> Problem in short is as following:
> after reINVITE from Cisco to negotiate T.38:
> 
> <--- SIP read from UDP:193.110.9.17:5060 --->
> INVITE sip:37166101111 at 159.148.78.220 SIP/2.0
> Via: SIP/2.0/UDP 193.110.9.17:5060
> From: <sip:3250890229 at 193.110.9.17>;tag=74ff1200077fff10ff000018ff29ff16
> To: "37166101111" <sip:37166101111 at 159.148.78.220>;tag=as32fabaec
> Call-ID: 46ba3dad03495f6f35426980334703d3 at 159.148.78.220
> CSeq: 103 INVITE
> Contact: <sip:3250890229 at 193.110.9.17;user=phone>
> Max-Forwards: 10
> User-Agent: MERA MSIP v.1.0.2
> Content-Type: application/sdp
> Content-Length:   183
> 
> v=0
> o=- 1272610573 1272610573 IN IP4 193.110.9.17
> s=-
> c=IN IP4 193.110.9.17
> t=0 0
> m=image 25296 udptl t38
> a=T38FaxRateManagement:transferredTCF
> a=T38FaxUdpEC:t38UDPRedundancy

The problem here is being caused by the re-INVITE occurring prior to
SendFAX() being started; this really should not be happening, as the
other endpoint should not re-INVITE until it knows that a FAX endpoint
is calling, but some of them do this anyway.

There is a fix for this problem in SVN Asterisk trunk already, and it
will be merged into the 1.6.2 branch in the next couple of weeks.

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