I’ve tried to set:
disallow=all
allow=speex16
In my IAX trunk config. It worked, ‘iax2 show channels’ displayed codec as ‘speex1’
Per RFC speex16 is not supported by IAX2 (tools.ietf.org/html/rfc5456#section-8.7).
What codec was actually used?
The RFC says that you need to look at the IANA registry to see the full list.
[quote] Refer to the IANA Registry for any additional IAX Media Format
values.
[/quote]
In any case, as these are just the internal codes used by Asterisk, IAX trunks between Asterisk end points will support all the codecs in common between the two Asterisks, so if the Asterisks know how to give a name to the codec, it is supported.