[Freeswitch-users] T.38 and Audiocodes or Patton gateway

[Tim St. Pierre]

>>> Is your Audiocode's ECM support badly broken? Spandsp's T.38 terminal
>>> and gateway engines have been tested with numerous systems, and ECM is
>>> normally OK unless the other system does something stupid - which
>>> unfortunately a number of T.38 implementations still do.

It might be, although it doesn't work with it turned off either.  These gateways have been in use
for about a year, going through Asterisk to a SIP trunking provider that uses Metaswitch, and for
the most part, they work well.  It's when I terminate the call to Freeswitch and SpanDSP that
problems arise, but only with this device.  I'm waiting to get one back from a customer, then I can
do a proper A-B comparison using wireshark.

> When ITSPs recommend turning off ECM, its just an admission of failure. 
> They are accepting that the networks are so poor they are unlikely to 
> get a 100% correct result, even after the permitted number of retries. 
> In other words, they are accepting that FAXes with numerous errors, like 
> we had in the bad old days before ECM, are the bold new standard for 
> service quality in the internet era. Wonderful, isn't it.

ECM is there for a reason.  Our upstream carriers are great (otherwise we would choose someone
else), but most of our customers are connecting over unmanaged DSL links, so there are going to be a
few glitches.  Testing with my own fax machine, ECM off usually ends up with a few bad lines, but
ECM on gives me clean faxes every time.

A lot can be said for machines too.  99% of the "half my faxes fail" calls come from customers with
HP all-in-one machines.  I have an old brother fax machine that someone was throwing away.  If I set
it up at the same customer site, they can fax without problems.  That usually convinces them to buy
a new fax machine.