[asterisk-users] iaxmodem / hylafax receive problem

[Kingsley Tart]

On Sun, 2010-01-17 at 23:28 -0800, Lee Howard wrote:
> Kingsley Tart wrote:
> > Jan 14 12:44:49.39: [ 3403]: <-- [9:AT+FRH=3\r]
> > Jan 14 12:44:56.39: [ 3403]: --> [0:]
> > Jan 14 12:44:56.39: [ 3403]: MODEM <Empty line>
> > Jan 14 12:44:56.39: [ 3403]: MODEM TIMEOUT: waiting for v.21 carrier
> > Jan 14 12:44:56.39: [ 3403]: <-- data [1]
> > Jan 14 12:44:56.39: [ 3403]: --> [2:OK]
> >   
> 
> iaxmodem cannot "hear" any fax signaling in the call.
> 
> > Jan 14 12:44:56.39: [ 3403]: <-- [9:AT+FRS=7\r]
> > Jan 14 12:45:26.39: [ 3403]: MODEM TIMEOUT: reading line from modem
> > Jan 14 12:45:26.39: [ 3403]: MODEM <Timeout>
> > Jan 14 12:45:26.39: [ 3403]: Failure to receive silence (synchronization failure).
> > Jan 14 12:45:26.39: [ 3403]: <-- data [1]
> > Jan 14 12:45:26.41: [ 3403]: --> [2:OK]
> 
> However, there is *some* kind of audio on the call.
> 
> It would seem that this test call is producing some kind of 
> long-duration bad audio sounds which are not detectable by the modem as fax.

Hi Lee,

Thanks for your reply.

The bit that's baffling me is that I've managed to get a friend to test
this from his fax machine and it worked. From my limited understanding
of faxing, it seems to be some kind of compatibility issue between
hylafax with the fax I'm sending my test calls from, which ties in with
what you're saying.

The other odd thing is that the fax machine that fails with this
asterisk/iaxmodem/hylafax server works on another virtually identical
box running a virtually identical setup that's installed in the same
rack and plugged in to the same telecoms switch. I've even copied the
hylafax configs directly over from the 'working' server. Both servers
are using the same model of Sangoma E1 card.

I've played with the chan_dahdi.conf file by trying it with and without
echo cancellation and have played around with the rxgain just to see if
it helped but no luck.

Do you know what I should look at next, or how to get more diagnostics
somehow?

-- 
Cheers,
Kingsley.