I agree , may be it's not allowed, but we were forced to do the
possibility to change media from 180SDP to 200SDP in order to work with
other equipment.

Thanks

Ira 

-----Original Message-----
From: Sweeney, Andrew (Andrew) [mailto:[EMAIL PROTECTED] 
Sent: Monday, February 19, 2007 4:12 PM
To: Christer Holmberg (JO/LMF); Ira Kadin; Sanjay Sinha (sanjsinh);
Miljanovic, Nebojsa (Neb); [email protected]
Subject: RE: [Sip-implementors] SDP in 2xx response after reliable 18x

Why is "Fake Forking" OK to do? What is the issue that the SDP can only
be changed during "Fake Forking" and if this is acceptable then it seems
that changing streams between 18x and 200 should be OK as well.

The overhead in handling a "Fake Forking" case seems to be unnecessary
and can affect call performance. 

Seems like a lot of older devices still allow the change of the SDP. I
think Broadsoft pre rel 14 does it this way.

Thanks
Andy


-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Christer
Holmberg (JO/LMF)
Sent: Thursday, February 15, 2007 7:06 AM
To: Ira Kadin; Sanjay Sinha (sanjsinh); Miljanovic, Nebojsa (Neb);
[email protected]
Subject: Re: [Sip-implementors] SDP in 2xx response after reliable 18x


Hi, 

>It can be the situation when the call originally is connected to some 
>media announcement server (connected - meaning getting RTP, for example

>to play ringback), than - to the final user. In that case the UAC has 
>to switch from the media in 18x SDP to the media in 200 SDP

It is not allowed, for the same dialog.

But, in your use-case you can use "fake forking" (see separte thread),
and use different To tags in the 18x and 200. Then the 18x (tag=x) can
be used for the announcement, and 200 (tag=y) be used for the UAS.

Regards,

Christer

> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Sanjay 
> Sinha (sanjsinh)
> Sent: Wednesday, February 14, 2007 8:37 PM
> To: Nebojsa Miljanovic; [email protected]
> Subject: Re: [Sip-implementors] SDP in 2xx response after reliable 18x
> 
>  
> Option 2 does not seem correct. Option 1 is correct and you may also 
> want to ignore the sdp in 200 OK, just treat it as if there was no sdp

> in 200 OK.
> 
> Sanjay
> 
> >-----Original Message-----
> >From: [EMAIL PROTECTED]
> >[mailto:[EMAIL PROTECTED] On Behalf
> Of Nebojsa
> >Miljanovic
> >Sent: Wednesday, February 14, 2007 12:30 PM
> >To: [email protected]
> >Subject: [Sip-implementors] SDP in 2xx response after reliable 18x
> >
> >Trying to get a feel on how various developers interpret RFCs 3261,
> >3262 and 3264.
> >
> >If you are acting as an UAC and you have received SDP in
> reliable 18x
> >response (i.e. PRACK was used), and then again that same SDP
> comes in
> >2xx, what will you do?
> >
> >1. Verify that 18x and 2xx SDPs are the same and accept it.
> >
> >2. Tear down the call since you consider SDP in 2xx as an invalid 
> >Offer.
> >
> >
> >Also, do you know of any UAs that require 2xx to contain SDP
> even after
> >Offer/Answer was done with 183/PRACK.
> >
> >Thanks.
> >
> >
> >
> >
> >_______________________________________________
> >Sip-implementors mailing list
> >[email protected]
> >https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
> >
> 
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