On Tue, 27 Feb 2001, Victor Kueh wrote:
> Dear Jonathan,
>
> Thanks for your reply. But could I confirm with you on something again.
>
> >
> > 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).
> >
I would also say that it is important that the UAS are ready to
receive media when it has sent 200 OK because the TCP/IP stack of UAS will
generate icmp errors otherwise. These icmp errors might confuse the other
end to stop sending media. Also, as an implementor of a firewall with SIP
support, I want to say that a firewall might for security reasons close
media flows where icmp errors are returned.
Sadly, I have seen SIP implementations that do not listen to the media
port before the ACK is received. I hope these implementations will be
corrected.
The same reasoning applies to the UAC sending the INVITE. Listen to the
media port when you put it in the SDP.
Thanks,
Lars
>
> So the UAS need not wait for ACK to arrive to send media stream (for a low
> post-pickup delay)? But strictly speaking, the UAS has to wait for the ACK
> to arrive before the call setup is complete at the UAS (my first
> question in my initial email)? Is that correct?
>
> Many thanks again for your precious time.
>
> Cheers,
> Victor
>
>
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Lars Berggren <mailto:[EMAIL PROTECTED]>
Intertex Data AB tel: +46-8-6282828
Sundbyberg, Sweden fax: +46-8-6286414
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