I have done alot of interoperability of SIP to PSTN and have run into similar
problems in the past. It is my understanding in terms of PSTN that 183 should
be allowed before or after 180 and yet media be accepted at the receiving end.
This would be analogous to a PSTN world scenario where-in CPG is allowed before
or after ACM. I have seen that 3COM phones (not supported anymore) accept 183
media even after 180.

Shashi

--- "Volety, Suryaprakash Rao (Prakash)" <[EMAIL PROTECTED]> wrote:
> I bumped into this problem the other day relating to sequencing of 180
> Ringing  and 183 Session Progress responses from UAS.
>  
> In the following call flow  (with either  Cisco  7960 or  Pingtel) User Agent
> Client  is  ignoring 183 and thereby failing to provide early media.
>  
>   SIP UAC                                   UAS
> 
> ---INVITE---->
> 
> ....            <-----------------  100 Trying
> 
>                  <--------------- 180 Ringing 
> 
>                  <--------------- 183 Session Progress
> 
>  
> 
>  
> 
> However if we send , from UAS,  183  followed by  and 180 responses  , then
> UAC is  providing early media.
> 
> Can someone tell me what should be the exact sequence of responses that RFC
> stipulates ?
> 
>  
> 
> Thanks,
> 
> Prakash
> 
> 


=====
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Shashi Kaligotla                         
(727) 588-2642 [Home]      AOL/Yahoo IM: shashionip
(727) 534-8357 [Cell]         MSN IM: shashidhar_k          
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