Preferred codecs

On client I have the following codecs:

ilbc
gsm
pcmU
pcmA

but when I connect every time pcmU is used. Is there (freepbx) any settings that force to use pcmU? When I uncheck pcmU and pcmA the gsm is used, but when I uncheck gsm (so only ilibc is elected there is a connection error .

So question is about default codecs, where can I set it? What do you think is it a proper order or not:

ilbc
gsm
pcmU
pcmA

It is hard to give any advice when you don’t tell us anything about your system.

Need system details and types of phones, trunks, etc.

FREEPBX - Stable-1.815.210.58, configured with PUBLIC IP with ASTERISK SIP SETTINGS:
NAT: yes
IP Configuration: Public IP

but I have found it on:

http://server/admin/config.php?display=sipsettings#

And make an order:
ilbc
gsm
speex
ulaw
alaw
g722
g723
g726

Clients: JITSI

What do you think - is it a proper order? I know it depends… Clients will be connected from JITSI via Internet - sometimes GSM Edge. The system is internal skype.