> -----Original Message-----
> From: Victor Kueh [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, February 22, 2001 9:25 AM
> To: [EMAIL PROTECTED]
> Subject: [Sip-implementors] ACK request
>
> Is it true to say that if an ACK request never reaches the UAS
> (after 7 transmissions of final response), the call setup is not
> successful on the UAS side?
Yes.
>
> How about the UAC side - since it has received
> the first final response, it would have thought that the call setup is
> successful, won't it? So what will happen then?
The UAC will time out if its using session timer, else it will time out if
it is using RTCP to do so. Otherwise, it times out through human
intervention after the person says "hello, hello!" a few times. This is an
unsolvable problem from a protocols perspective. Its the byzantine armies
problem.
>
> Also in which state/stage, should the UAC be ready to
> send/receive media streams? How about for UAS?
UAC should be ready to receive after INVITE. Prepared to send after 200 OK.
UAS shoudl be ready to receive after 200 OK, and may send after 200 OK
(indeed, this is needed to deal with a low post-pickup delay).
Both of the above assume that SDP was present in the INVITE/200.
-Jonathan R.
---
Jonathan D. Rosenberg 72 Eagle Rock Ave.
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.cs.columbia.edu/~jdrosen PHONE: (973) 952-5000
http://www.dynamicsoft.com
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