IAX extensions don't want to connect to new install


I have been porting our phone system from one machine to another and upgrading things along the way. We have the following installed and running:

Centos 5.5 (updated as of a week ago)
Asterisk 1.6.2 (from Digium’s repository
FreePBX 2.8
Asterisk Free Fax

And with this I have working

  • all the SIP devices
  • 2 SIP trunks
  • Digium TDM400P with 1xFXO, 2xFXS
    -> POTS line and phones working, redirection to the fax machine working on incoming fax detect

Unfortunately what I don’t have working are the IAX devices. Everything seems to be configured correctly but they don’t connect. There is no error (that I perceive) in the logs. I am sure that the ip address, user names and passwords are correct. I have tried both our IAX hard-phones as well as the Zoiper and WiPhone soft-phones.

Any suggestions as to what I can do to diagnose this problem?