Question : trixbox: no audio to/from/between extensions outside the PBX lan.

I have a trixbox on my LAN. The first time I installed it I had success communicating with remote SIP phones. Then I reinstalled trixbox and now remote uses can't hear or be heard on any call they make or receive.

2 users in the remote LAN can call each other but not hear each other.

Answer : trixbox: no audio to/from/between extensions outside the PBX lan.

Usually this problem is related to koszegi's reference above, make sure your sip_nat.conf file has:
nat=yes
externip=xxx.xxx.xxx.xxx