[SR-Users] Missing ACK

Klaus Darilion klaus.mailinglists at pernau.at
Fri Jul 2 17:16:33 CEST 2010



Am 02.07.2010 15:54, schrieb Claudio Furrer:
>>>>> Hi, I have a similar issue,
>>>>
>>>> It is not possible to debug this issue without full SIP trace!
>>>>
>>>> ngrep -Wbyline -t -d any port 5060
>>
>> I find it unpleasant to read such a trace. Please really use ngrep to get a
>> nice formated SIP trace, or supply the pcap file.
>>
>
> Ok, here it goes again.
>
> Pay attention to the "200: OK" response from the PSTN-GW. I think its Contact
> header should be read by the Cisco GW (calling party), and then send its
> ACK-request with R-URI based on that Contact. But it doesn't happen. Then here i
> think this is the failure. (rfc3261, section 12.1.1 and 12.2.1.2). May i am
> wrong..
>
> What do you think?
> I'd appreciate your comments.

You are right. Caller behaves wrong, it should send ACK with 
RURI=ContactOf200Ok.

Maybe this is a buggy NAT traversal feature of Caller (Cisco?) which can 
be turned off.

If you can't fix it at Caller-side, you can make some workarounds at the 
proxy (if it is a fixed routing to the other gateway)

regards
Klaus



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