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<DIV dir=ltr align=left><SPAN class=053585700-23092010><FONT color=#0000ff
size=2 face=Arial>Excuse me for jumping, but I'm trying to locate information on
"codec 83" and can't find anything, can anyone recommend a different forum or
list I can check?</FONT></SPAN></DIV><BR>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left>
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<FONT size=2 face=Tahoma><B>From:</B> asterisk-dev-bounces@lists.digium.com
[mailto:asterisk-dev-bounces@lists.digium.com] <B>On Behalf Of </B>federico
cabiddu<BR><B>Sent:</B> Wednesday, September 22, 2010 10:20<BR><B>To:</B>
asterisk-dev@lists.digium.com<BR><B>Subject:</B> [asterisk-dev] Fwd: T38 and
codecs negotiation<BR></FONT><BR></DIV>
<DIV></DIV><BR><BR>
<DIV class=gmail_quote>---------- Forwarded message ----------<BR>From: <B
class=gmail_sendername>federico cabiddu</B> <SPAN dir=ltr><<A
href="mailto:federico.cabiddu@gmail.com">federico.cabiddu@gmail.com</A>></SPAN><BR>Date:
2010/9/22<BR>Subject: [asterisk-users] T38 and codecs negotiation<BR>To: <A
href="mailto:asterisk-users@lists.digium.com">asterisk-users@lists.digium.com</A><BR><BR><BR>Hi,
<DIV>I'm working with asterisk 1.4.35 and found an issue regarding codecs
negotiation when T38 is enabled (t38pt_udptl=yes).</DIV>
<DIV>In particular if the INVITE sdp contains no allowed codec the call is not
rejected with "488 - Not acceptable here" but it goes through and the 200 OK SDP
is as follows:</DIV>
<DIV><BR></DIV>
<DIV>
<DIV>v=0</DIV>
<DIV>o=root 27285 27285 IN IP4 xxx.xxx.xxx.xxx</DIV>
<DIV>s=session</DIV>
<DIV>c=IN IP4 xxx.xxx.xxx.xxx</DIV>
<DIV>t=0 0</DIV>
<DIV>m=audio xxxxx RTP/AVP </DIV>
<DIV>a=silenceSupp:off - - - -</DIV>
<DIV>a=sendrecv</DIV>
<DIV><BR></DIV>
<DIV>or</DIV>
<DIV><BR></DIV>
<DIV>
<DIV>v=0</DIV>
<DIV>o=root 27285 27285 IN IP4 xxx.xxx.xxx.xxx</DIV>
<DIV>s=session</DIV>
<DIV>c=IN IP4 xxx.xxx.xxx.xxx</DIV>
<DIV>t=0 0</DIV>
<DIV>m=audio xxxxx RTP/AVP 96</DIV>
<DIV>a=rtpmap:96 telephone-event/8000</DIV>
<DIV>a=fmtp:96 0-15</DIV>
<DIV>a=silenceSupp:off - - - -</DIV>
<DIV>a=sendrecv</DIV>
<DIV><BR></DIV>
<DIV>if in the originating INVITE there was the a line for telephone-event
mapping.</DIV>
<DIV>Looking chan_sip.c I understood that the problem is related to t38
capabilities and in particular at row 5636:</DIV>
<DIV>
<DIV><BR></DIV>
<DIV>if (!newjointcapability) {</DIV>
<DIV> /* If T.38 was not negotiated either,
totally bail out... */</DIV>
<DIV> if (!p->t38.jointcapability ||
!udptlportno) {</DIV>
<DIV>
ast_log(LOG_NOTICE, "No compatible codecs, not accepting this
offer!\n");</DIV>
<DIV> /* Do NOT
Change current setting */</DIV>
<DIV> return
-1;</DIV>
<DIV> } else {</DIV>
<DIV> if
(option_debug > 2)</DIV>
<DIV>
ast_log(LOG_DEBUG, "Have T.38 but no audio codecs, accepting offer
anyway\n");</DIV>
<DIV> }</DIV>
<DIV> }</DIV>
<DIV><BR></DIV>
<DIV>As I understand if t38 is globally enabled p->t38.jointcapability
and udptlportno are always true even so the call is never rejected.</DIV>
<DIV>As this behavior caused me some problems with a customer I modified, for
the moment, the line 5638 as follows:</DIV>
<DIV><BR></DIV>
<DIV>if (!p->t38.jointcapability || !udptlportno || p->t38.state ==
T38_DISABLED)</DIV>
<DIV><BR></DIV>
<DIV>cause if I understand well the code if there is no fax request in the
INVITE SDP p->t38.state is set to T38_DISABLED.</DIV>
<DIV>This did the trick for me but I don't know the implications of such change
and if it is correct to manage it this way.</DIV>
<DIV><BR></DIV>
<DIV>Kind regards,</DIV>
<DIV><BR></DIV>
<DIV>Federico Cabiddu</DIV>
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