I've got 20 iaxmodems running on a centos box with asterisk 1.6 & hylafax. Both inbound, outbound and internal work fine.
The only issue I am having is that about 50% of the time the channel still shows as active in asterisk when the fax has finished sending / receiving, ie "iax2 show channels" in the asterisk CLI will give me a whole bunch of:
"IAX2/fax001-11406 127.0.0.1 (None) 11406/02294 00005/00006 00000ms -0001ms 0000ms ulaw"
Note that the modem(s) are actually free and will continue to send/receive calls, but will eventually appear in asterisk to be active on multiple channels, as such this isn't preventing hylafax from working, but is obviously quite annoying and will prevent things like 'core restart when convenient' from working.
I'm not sure if this would be an asterisk or iaxmodem issue (although I do have other iax channels/trunks that do not do this).
This is what I have in my iax.conf:
my /etc/iaxmodem/tty files are in this format:
If anyone can think of anything I can try to get this sorted would be much appreciated.
I've never used Asterisk 1.6. Maybe you should try with 1.4.