[Freeswitch-users] Fax T.38: How to deal with NSF (NSS)?

[Peter Steinbach]

Hello,

we have a number of fax machines attached via a Grandstream ATA to a
Freeswitch. Fax devices are Brother MFC. Freeswitch works in
t38-passthru mode.

In the last weeks we see (maybe due to software update?), that the fax
devices detect, that they are siblings with extended feature sets, and
then one side switches to "non standard facilities" mode by sending an
NSF signal (resp NSS in wireshark). The opposite side then answers with
"failed to train" (FTT). This always breaks the fax transmission. We
also asked Brother to send us an advice, how to disable NSF in the fax
device, but these codes did not work. The fax devices are continuing to
send NSF. Besides that we have no control of the opposite fax device,
who are initiating NSF.

So I am asking here: How are you dealing with NSF? How did you solve
this issue?

-- 
With kind regards
Peter Steinbach 

Telefaks Services GmbH
mailto:lists (att) telefaks.de
Internet: www.telefaks.de