[asterisk-users] IAXy behind NAT, unable to transfer?

[Jeff Iddings]

IAX Provider--> Asterisk/NAT Firewall--> IAXy (192.168.0.x)

When a call comes into the Asterisk box, it then rings the IAXy. 
When the IAXy is answered, I get.. 

-- IAX2/homeiaxy-6 answered IAX2/teliax-4
-- Channel 'IAX2/teliax-4' unable to transfer
-- Channel 'IAX2/homeiaxy-6' unable to transfer

This is the same behavior when calling outbound, and I've tried a few other calls to other IAX-capable boxes -- same results. I'd ideally like the IAXy to talk directly to the IAX provider and bypass the Asterisk box after the call is setup. 

I presume this is just a limitation of IAX and/or the IAXy, but maybe someone could advise me if that is actually the case?

Regards,

Jeff