Where should I configure so that G722 is used inside the organization where possible, and G711A is used on the trunk?

Question

Asterisk

There is FreePBX 2.09 on asterisk 1.8, a trunk to which only G711A can be called, as well as SPA502G phones.
Tell me, please, where you need to configure it so that G722 is used inside the organization, and G711A is used on the trunk?
It is done so that the server does not recode, but the entry is needed, so canreinvite=no.

Answer 1

The SIP_CODEC and SIP_CODEC_OUTBOUND variables in the dialplan. Don't know if this applies to FreePBX

Answer 2

Applicable, but not really, because rewriting plans in this system sometimes breaks its logic :)
I thought there was some parameter that would force the asterisk to look for common codecs among peers.

Answer 3

For a trunk, write:
disallow=all
allow=alaw
For extensions:
disallow=all
allow=g722