Trying to complete transmission

[olavio@microetc.com (Olavio Junior)]

Hi all,
I installed and compiled the HylaFAX, now I'm trying to send a fax 
using:
sendfax -d ###-#### /etc/test
Although the system dials out and connect with the remote fax machine, 
it does not send the file and hangs up.
After third attempt, I get a message "Unspecified transmit Phase B 
error. ..."
I'm Using an UsRobotics Sportster 28.8 on Com1 (cua0) with Linux 
Slackware 96
I already tryied to configure as Class 1 and 2.0
Does any one has a config.file that works with UsRobotics ???
Please HELP !
TIA!