On Tue, Jul 10, 2012 at 11:51 AM, Stephen Wilde <wstephen80@gmail.com> wrote:

Is this message flow valid?

FS ---------------- MyProvider

---> INVITE (w/SDP G729, G711a, G711u)

<--- 100 Trying

<--- 183 Session Progress (w/SDP G729, G711a, G711u)

<--- 200 OK (w/SDP G729, G711a, G711u)

What is strange to me is that my provider send back a 183 Session Progress with all codec list of Freeswitch INVITE (I expect only the choosen codec).

It's this message flow correct?

Although strange, I think per spec is correct.

Section 7, mentions multiple answers are valid to the offer and it MAY send media in any of the accepted streams and MUST send media using one of the accepted formats and it SHOULD use the first one listed in the answer.

Anyone feel free to correct me if my understanding is wrong, as I just started going thru the SIP related specs myself to troubleshoot and support this kind of scenarios.

Moises Silva
Manager, Software Engineering

msilva@sangoma.com

Sangoma Technologies

100 Renfrew Drive, Suite 100, Markham, ON L3R 9R6 Canada

t. +1 800 388 2475 (N. America)

t. +1 905 474 1990 x128

f. +1 905 474 9223