[Asterisk-Users] Some info about Cisco's 79xx, and Sipura's phones

[Irakli Natsvlishvili]

Hello folks,

I've did some tests with different phones and Asterisk last two days and 
here are some results, which I want to share with audience.

Cisco's 79xx and Sipura's phones/adapters on INVITE always reply with their 
preferred codec.

So, for example, if Cisco's/Sipura's phone has preferred_codec g729a(18) and 
it receives INVITE from UA which has preferred codec ULAW(0), it will always 
reply with g729 and ignore what is preferred codec of calling party.

Also, if two UAs have canreinvite=yes in SIP.CONF, then there is no 
difference in which order codecs are listed. If Cisco/Sipura's UA is called, 
then resulted codec after re-INVITEs will be preferred codec of CALLED 
party.

There are other UA's which reply with the preferred codec of calling party. 
For example, SNOM and Grandstream behave this way.

Hope this helps.

I.N.