flexfax: Unspecified Transmit Phase B error

[David Nelson <dnelson@psa.pencom.com>]

HylaFAX v4.0pl1 under RedHat 4.1 using precompiled rpm from sgi.com; USR
Sportster 56K/X2; Firmware: ???

I tired searching the online HylaFAQ and got "The requested URL
/cgi-bin/search.pl was not found on this server."  I read through some
potential condidates and didn't find anything that matched this. I've
removed the binary I/O as requested and I hope that the included trace is
not inapropriate (13 lines).

After finally getting the modem to dial I am unable to maintain a
connection.  The modem dials, the remote answers, they
handshake/negotiate, then hangup. 

Oct 10 01:21:47.84: [ 1514]: DIAL 5551212
Oct 10 01:21:47.84: [ 1514]: <-- [12:ATDT5551212\r]
Oct 10 01:21:59.68: [ 1514]: --> [4:+FCO]
Oct 10 01:22:02.72: [ 1514]: --> [39:+FNF:^[+FCI:"5555551212"^T+FIS:]
Oct 10 01:22:02.72: [ 1514]: REMOTE NSF "^[+FCI:"5555551212"^T+FIS:"
### 6 Lines of I/O to remote fax ###
### 0 Lines of I/O from remote fax ###
Oct 10 01:22:43.68: [ 1514]: REMOTE HANGUP: Unspecified Transmit Phase B
error (code 20)
Oct 10 01:22:43.69: [ 1514]: SEND FAILED: Unspecified Transmit Phase B 
error
Oct 10 01:22:43.69: [ 1514]: <-- [5:ATH0\r]
Oct 10 01:22:43.92: [ 1514]: --> [4:ATH0]
Oct 10 01:22:43.92: [ 1514]: --> [2:OK]
Oct 10 01:22:43.92: [ 1514]: SESSION END

This is the second fax program that I've tried; hoping that HylaFAX would
better handle the problem.  Is my problem really cruddy hardware or
something else?

Thank you,
David Nelson