[Freeswitch-users] Selective problem with outbound calls

[JT Bock]

Hi,

Hoping someone might have some insight...

I currently have a Debian 7 system (freeswitch 1.4) with Aastra 6731i 
phones and a single Polycom 335. Everything works fine.

I built a Debian 8 system (freeswitch 1.6) as a drop-in replacement. 
Inbound calls work fine on the 2 different brands of phones (Aastra, and 
Polycom), but the Aastra phones cannot make outbound calls. Or rather, 
they can, but there is no audio. Outbound calls via the Polycom work 
fine.  I did packet captures when making an outbound call with each type 
of phone, and when using the Aastra phones, there is no response 
received by the FS box after the Invite.

I literally unplug the Debian 7 system and plug in the Debian 8 system. 
They are identically IP'ed, same SIP and RTP ports, etc.  I can move the 
Debian 8 box to e.g. my home network, and then the Aastra phones work fine.

So, it seems this is some kind of firewall/nat problem, but why would 
the Polycom still work? Is there some configuration parameter on the 
Aastra phones I should look at?

Any thoughts appreciated.

Thanks,
Tim