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Thread: CANCEL message immediately following a re-INVITE




CANCEL message immediately following a re-INVITE
user name
2006-09-25 15:35:00
Hi,

I have checked out the latest codes from the CVS and
successfully built the 
simpleOpal for making outgoing calls. But simpleOpal failed
to establish 
connections with the proxy server. It sends a CANCEL message
immediately 
following a re-INVITE. The details are as follows.

1) simpleOpal => Create INVITE message with CSeq = 1 to
invite the called 
party.
2) Proxy server sends back a 401 Unauthorized message with
authenticate 
info. (CSeq=1)
3) simpleOpal => Sends back with an ACK message with CSeq
= 1
4) Proxy sends back 100 Trying message.
5) simpleOpal => Create another INVITE message with CSeq
= 2 to re-invite 
the called party.
6) simpleOpal => Create a CANCEL message with CSeq = 2
7) Proxy responds with 100 Trying.
8) Proxy responds with 487 Transaction cancelled.

In step 6, simpleOpal sends a CANCEL message that causes the
problem. By 
tracing the code, I have commented out the following line in
sipcon.cxx line 
1818-1821 (SIPConnection::OnReceivedResponse), and then it
can successfully 
make outgoing calls as well as play DTMF over the line.

      for (i = 0; i < invitations.GetSize(); i++) {
        if (&invitations[i] != &transaction)
          invitations[i].SendCANCEL();
      }

Can anyone give me some hints why in step 6, simpleOpal
sends a CANCEL 
message? Am i doing something wrong? What is the correct
way? Thanks in 
advance.


Ting Liu


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