Innocent Evil wrote:
IP Phone --> SIP Server --> Asterisk
--> (Voice Mailbox)
(G723.1, G729) -> (GSM) -> (GSM, G729) GSM coded file
The SIP server (if it's a proxy like SER) doesn't matter for codec
negotiation, because it just does the SIP signalling.
So if your phone supports G.723.1 and G.729, then Asterisk has to
support one of these (for G.729 you need a license from Digium, G.723.1
is only supported in pass-thru-mode AFAIK, so not usabe here).
Andy