[Asterisk-Users] No audio when calling between internal phones

[Gareth Blades]

I am running the latest CVS version of Asterisk.
Calls between an IAX client and SIP phones (Grandstream SP2000 and
Sipura SPA-841) works fine and so do external call over the Internet
from the SIP desk phones.

However when I call from either the Grandstream/Sipura phones to another
one I get no audio. I have the G711 ulaw codec defined as the preferred
on on all phones.

Any idea what is going wrong?
I am guessing it is something to do with native transfers which is
performed in this situation.