dear, I'm testing Zoiper Android on a Sangoma FreePBX 18.104.22.168.
I'm using IAX2 connection and I'm not able to place Calls with a codec different from Alaw. I enable GSM and Speex but only with alaw codec it can place calls.
On Asterisk settings IAX I have enabled all codecs.
The Call hangs up without ringing client.