I’m trying to force GSM when I call on certain extension but I’m getting connected with “ulaw”
Which is not suitable when bandwidth is low and slow.

my phone is iax-322

in iax.conf

[iaxy-322]
… disallow=all allow=gsm allow=ulaw allow=alaw

[zoiper_kathy_old_phone]
… disallow=all allow=gsm allow=ilbc allow=ulaw allow=alaw allow=speex

I’ve define “allow=gsm” in as the first codec so it should take priority, isn’t it?
but when I call I get connected with “ulaw”

Incoming call is getting IN as GSM from that phone but outgoing is going out as “ulaw” why?

In “zoiper” the GSM is enable as well and as first codec.

Called IAX2/zoiper_kathy_old_phone
— Call accepted by 66.18.210.217 (format ulaw)