[OpenSIPS-Users] Troubleshooting unabsorbed 200 OK retransmissions

[Michael Schloh von Bennewitz]

Hello Bogdan,

On Tues., Jan. 30, 2013, Bogdan-Andrei Iancu wrote:
>On 01/27/2013 06:28 PM, Michael Schloh wrote:
>>An upstream PSTN gateway is retransmitting 200 OK just some hundreds
>>milliseconds after the first 200 OK (following my outgoing INVITE.)
>>My OpenSIPS 1.7.2 on Solaris 11 AMD64 is sending both 200 OK
>>messages to the UAC which initiates the INVITE. The retransmitted
>>200 OK messages are identical.
>>
>>[...]
>>
>>How can I force OpenSIPS to absorb the 200 OK retransmissions?
>>
>The retransmissions for 200 OK are end-2-end, which means their are
>transparent for the proxies - that's what the RFC says. The 200 OK  +
>ACK exchange is end-2-end confirmation and proxies are not absorbing
>any retransmissions here.
>
Okay that makes sense, so not only is OpenSIPS doing its job
correctly but that I shouldn't try to adjust this behaviour in
respect of RFC3261.

What doesn't make sense is that the upstream gateway is waiting
sometimes just 300 milliseconds to retransmit, when they know
there will be SQL lookups, DNS lookups, and so on.

The operator told me that the timer value 500 ms is standard
practice for 200 OK, not sure if he's right about that or if
there's any good reason for it.

Thanks for the great answer, by the way.

Regards,
Michael