Jean-Yves Avenard wrote:
What are the advantages of T31 over T30 ?
T.30 is the spec for fax protocol. T.31 is the spec for a Class 1 fax
modem.
So T.31 is a layer that allows something else to perform fax protocol
(T.30) through it.
There may be some intrinsic value to handling faxing through a T.31
interface, adding certain default tolerances or behaviors; however, I'm
not certain what they would be.
Thus in the IAXmodem + HylaFAX scenario T.30 is being performed by the
HylaFAX Class 1 driver whereas with rxfax/txfax T.30 is being performed
by rxfax/txfax/spandsp.
Neither approach is inherently better than the other, I would suspect;
however, I would guess that HylaFAX, having been around for 17+ years
now, and with me and others watching hundreds and hundreds of thousands
of faxes pass through it and continually tweaking and improving the
software... well, I would suspect that it's a bit more mature than the
other approach (no offense at all intended to Steve).
One thing I'm missing right now (but I haven't looked at what can be
done to fix it), is that rxfax add useful bits of information at the
top of the page (faxid, time of call etc), while hylafax leave it
empty.
HylaFAX, especially in ECM mode, takes effort in preserving the image
data sent by the sender exactly as the sender delivered it. So by
default HylaFAX doesn't get into the business of tampering with the
image - whether that be changing image compression formats, resolution,
or adding markings to the image itself. If you want to add that kind of
information to the image then you can do it in your delivery mechanism
(usually FaxDispatch)... however all of the information that you seek is
available in the TIFF tags which will be displayed with the 'faxinfo'
utility or through the hfaxd-client protocol.
yesterday, while doing my test, i found out that iaxmodem would
unregister from asterisk once in a while (running on the local
interface), what i've done around that is set up more iaxmodem than I
need, however at one stage I had to restart the iaxmodem for it to
reconnect as after a few minutes there were still non-registered
modem.
I assume that you're using iaxmodem-0.1.16. If not, then you should
update. If you are, then you'll probably want to take that bug report
to the iaxmodem forums ... see http://iaxmodem.sourceforge.net.
If you're using hylafax.org's HylaFAX and running faxaddmodem then it
has the tendency to kill off the iaxmodem process... and that could
cause what you're seeing.
Thanks,
Lee.
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