RE: [Serusers] Who is violating SIP protocol here, SER or voice-ISP? - sr-users

21 Oct 2004

Jeremy,
I don't know if you got this answered already or not - I'm not seeing
the subject popping back up...

My PBX Gateway was doing the same kind of thing: calls were timing out
after about 1 minute (45 seconds once, and 60 seconds another time).  It
turns out that the loose-route processing wasn't working right.  If I
put the:
if (loose_route()) {
 	if (!t_relay()) {
		sl_reply_error();
	};
	break;
};

Line after the registration and "if (uri==myself){stuff}; blocks, then
I'd time out.  If the Loose_route() processing was up earlier, near the
top of the ser.cfg (like in the demo), then my PBX Gateway wouldn't time
the calls out.

Rob

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...
  -----Original Message-----
 From: serusers-bounces(a)lists.iptel.org 
 [mailto:serusers-bounces@lists.iptel.org] On Behalf Of Jeremy M. Dolan
 Sent: Thursday, October 07, 2004 11:54 AM
 To: serusers(a)lists.iptel.org
 Subject: [Serusers] Who is violating SIP protocol here, SER 
 or voice-ISP?

 I will attach a full SIP conversation to this e-mail, but 
 here is the summary of what seems to be happening.

 I place a call from my phone here, behind NAT. This contacts 
 a SER server with nathelper/rtpproxy out on the 'net, which 
 then forwards the requests to Masergy (www.masergy.com), who 
 provide us with LD VoIP service. Everything proceeds fine 
 until the "OK" reply from Masergy signalling the call has 
 been answered. Here's the transaction there:

    Masergy port 29436 -> SER port 5060 "OK"
    SER port 5060 -> My Phone port 5060 "OK"
    My Phone port 5060 -> SER port 5060 "ACK"
    SER port 5060 -> Masergy port 29436 "ACK"

 Masergy never receives that last packet.

 However, my phone receives all of the information it needs to 
 establish the RTP connection. It does so, and the call 
 appears to be working fine.
 Meanwhile, Masergy's SIP server continues to resend "SIP/2.0 200 OK"
 messages (still from port 29436) every few seconds, waiting 
 for a reply.
 After ~35 seconds of not hearing back, it assumes the worst 
 and sends a "BYE", tearing down a call that was going swell, 
 as far as the two humans involved were concerned.

 I've spoken with the relevant tech at Masergy, and their 
 determination is that our SIP proxy should be sending all SIP 
 traffic to port 5060, regardless of what they may be 
 transmitting from.

 I just built the very latest CVS version of SER 
 (0.8.99-dev8), and am seeing the same behavior. Is this a 
 protocol violation on either side?
 (Transmitting to a non-5060 port, or not listening for a 
 reply on a port that was just transmitted from). Is there a 
 way to force SER to always use 5060? (Which itself probably 
 breaks protocol for some cases, which we aren't currently 
 dealing with).

 Thank you for any info.

 Jeremy

 --
 Jeremy M. Dolan <mailto:jmd@pobox.com> <http://jmd.us/>
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