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<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'>Hi, im trying to build a UAC and I'm coming up with
some trouble whenever I receive a SIP 491 Request Pending Response. This
happens because I try to place a call on hold using an Invite request rigth
before Asterisk sends me a Re-Invite for the same call. I respond to the 491
response with an ACK however for some strange reason Asterisk doesn't accept
the ACK and insists on retransmitting the 491 Response. Asterisk replies with
the following 491 response: <br>
<br>
SIP/2.0 491 Request Pending <br>
Via: SIP/2.0/UDP
10.110.7.89:5070;branch=z9hG4bK5a668c33f196837c3602266b23b389e0;received=10.110.7.89
<br>
From: <sip:30001@10.110.7.20:5070>;tag=SIPTester <br>
To: <sip:30008@10.110.7.20>;tag=as2ea72122 <br>
Call-ID: 0dd43bb5a64eb5a2fb0114193821f037@10.110.7.89 <br>
CSeq: 5 INVITE <br>
User-Agent: Asterisk PBX <br>
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY <br>
Supported: replaces <br>
Content-Length: 0 <br>
X-Asterisk-HangupCause: Normal <br>
<br>
<br>
<br>
And I send the following ACK: <br>
<br>
<br>
<br>
ACK sip:30008@10.110.7.20 SIP/2.0 <br>
Call-ID: 0dd43bb5a64eb5a2fb0114193821f037@10.110.7.89 <br>
Max-Forwards: 70 <br>
From: <sip:30001@10.110.7.20:5070>;tag=SIPTester <br>
To: <sip:30008@10.110.7.20>;tag=as2ea72122 <br>
Via: SIP/2.0/UDP 10.110.7.89:5070;branch=z9hG4bK5a668c33f196837c3602266b23b389e0
<br>
CSeq: 5 ACK <br>
Content-Length: 0 <br>
<br>
However this doesn't seem to be valid because Asterisk insists be resending the
same 491 Response until it sends 6 messages and the decides to destroy the
dialog: <br>
<br>
</span><a href="http://www.voip-info.org/boards/Aug%2021%2011:21:06"><span
lang=EN-GB>Aug 21 11:21:06</span></a></font><span lang=EN-GB> WARNING</span><a
href="http://www.voip-info.org/boards/9686"><span lang=EN-GB>9686</span></a><span
lang=EN-GB>: chan_sip.c:1967 retrans_pkt: Maximum retries exceeded on
transmission 0dd43bb5a64eb5a2fb0114193821f037@10.110.7.89 for seqno 5 (Critical
Response) — See doc/sip-retransmit.txt. <br>
</span><a href="http://www.voip-info.org/boards/Aug%2021%2011:21:06"><span
lang=EN-GB>Aug 21 11:21:06</span></a><span lang=EN-GB> WARNING</span><a
href="http://www.voip-info.org/boards/9686"><span lang=EN-GB>9686</span></a><span
lang=EN-GB>: chan_sip.c:1989 retrans_pkt: Hanging up call
0dd43bb5a64eb5a2fb0114193821f037@10.110.7.89 - no reply to our critical packet
(see doc/sip-retransmit.txt). <br>
<br>
Does anyone have a clue of what it is I'm doing wrong? Do I have to send a
CANCEL request of the hold's INVITE? <br>
<br>
</span>Thanks in advance!<font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><strong><b><font size=2 face=Arial><span style='font-size:
10.0pt;font-family:Arial'>Joaquín </span></font></b></strong><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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