[SR-Users] CSeq values in dialog OPTIONS keepalives

Daniel-Constantin Mierla miconda at gmail.com
Fri Jan 3 16:16:51 CET 2020

when the call is established, there is one request (the INVITE) from caller
to callee. Then the ACK also from caller to callee. But there is no request
from callee to caller at that moment. Each side is using its own cseq
value, the callee doesn't have to use the latest cseq from caller plus one
when it sends a request (like a re-INVITE or the BYE). In practice the cseq
0 is not usually used by an UA, so that's why the keepalive for that
direction is using it.


On Thu, Jan 2, 2020 at 10:07 PM Alex Balashov <abalashov at evaristesys.com>

> On Thu, Jan 02, 2020 at 09:26:23PM +0100, Daniel-Constantin Mierla wrote:
> > the cseq 0 is because in that direction was no request sent
> > end-to-end.
> Also, sorry, but I didn't quite understand this.
> --
> Alex Balashov | Principal | Evariste Systems LLC
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Daniel-Constantin Mierla - https://www.asipto.com
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