[asterisk-users] Asterisk + iaxmodem + hylafax makes sometimes wedged for hylafax

[Lee Howard]

On 07/04/2013 08:49 AM, Gianni Fioretta wrote:
> Hi, we have a faxserver with Asterisk, IAXModem and Hylafax.
> Faxes come from a SIP trunk to Asterisk, then are forwarded throught 5 IAXModems managed with Hylafax.
> Hylafax users can also send faxes to these modems and Asterisk send them throught the SIP trunk.
> We also have a dedicated modem used only for sending faxes coming from an Hylafax dedicated user.
>
> Sometimes Hylafax reports that a modem is wedged and this modem remain wedged until we restart IAXModem daemon. When all modems becames wedged the server can't send and receive any fax.

IAXmodems do wedge sometimes, and I currently advise users to develop a 
"resetmodem" (see 'man wedged') to automatically reset the iaxmodem.

It's not clear to me why the iaxmodems sometimes wedge.  It essentially 
means that somewhere the iaxmodem code is either stuck in an endless 
loop, blocking on a read somewhere that shouldn't block, or something of 
that nature.  If you could capture the gdb or strace of an iaxmodem as 
it gets wedged, then that would be most-helpful.

However, I can tell you that the wedging occurs more-frequently in cases 
where there are other problems such as line audio quality issues or lots 
of non-fax numbers being used accidentally.  So your use of SIP (VoIP) 
for what should be a lossless data channel is probably a factor there.

Thanks,

Lee.