Re: flexfax: Pb: Hylafax -rockwell Phase D error

[David Woolley <david@djwhome.demon.co.uk>]

> Aug 04 14:22:33.12: [17809]: SEND recv RTN (retrain negative)

Either:

- the line quality is so bad, or the signal is being corrupted by something
  like data overruns; or

- the sender is violating the fax coding rules; or

- the receiver is incorrectly rejecting validly coded data.

As a result, the receiver is inferring that the line quality has changed 
since the initial calibration (training) of the modems for that session and
has rejected (negative) the page and requested a recalibration (retrain).

There was a lot of discussion on this earlier in the year
(...multiple errors..., or might have been multiple transmissions).

Merging on and off list contributions, it would appear that the standards
require that RTN be treated differently from RTP (the page was acceptable,
but the line seems to be degrading), but that, pragmatically, the need
for a retrain is not usually detected by monitoring the analogue quality
of the signal and systematic errors, like coding errors are so common,
that, in the view of one developer of commercial fax software, the only
safe approach was to treat RTP and RTN alike.  Hylafax does honour the
N in RTN.

You should check that your flow control is sound (probably hardware), the
modem to computer rate is fast enough (needs to be somewhat more than 125%
of the modem to modem rate, and that you are using an RIP that doesn't 
generate invalid fax encodings in the compression modes that you are 
allowing.