[SIPForum-discussion] question on PRACK

[raj kumaradass]

Typical use of 183 SessionProgress is in earlyMedia cases to allow  UAC to
hear ring/busy tone, or a recorded announcement in calls through a gateway
into the PSTN as it is a end-end response with dialog associated(as opposed
to 180ringing).

Perhaps this doesn't have to with PRACK. Does the problem persist when you
have 100rel support cases alone?.

danke!
...raj

On Thu, May 12, 2011 at 4:27 AM, Raghul Prasanna <raghul82 at yahoo.co.uk>wrote:

> Hello all,
>
> One of our carrier requires support for PRACK.
>
> When the carrier sends 183 Session Progress, we send PRACK and receive 200
> OK for the PRACK.
>
> Then they again send 180 Ringing and our SBC rejects the call.
>
> I believe we are right here to reject the call, because the carrier
> shouldnt be sending 180 ringing after receiving PRACK for 183 Session
> Progress. Please let me know.
>
> Also if possible please point me to any rfc which says PRACK to 183 should
> not be followed by 180.
>
> Thanks,
> Raghul
>
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