3Com U.S. Robotics 56k Message Modem (External) - Newbie question

[J Simpson V21]

Hi

I recently purchased the above external modem as my internal modem was
apparently a softmodem and I didn't have the skill to make it work with
RedHat 9.

I have used the Internet Configuration Wizard to set up the modem, when I
click on "activate" it says "failed to activate ppp0 with error 8.  But I
see light flashing on the modem.

I have also set up kppp and when I click on connect it says "modem ready" (I
see lights flashing on the modem), then it says "initalising modem" and
seems to get stuck.  The TR light on the modem remains on then.

TR in the  book says 'ON if modem receives a DTR signal from computer.
Always on (modem ignores DTR) if the DTR override is ON (&DO)'  I'm not sure
what that means.  I purchased the modem second user, so I'm wondering if it
is a problem with the modem.

I don't believe it is the serial port as I have 2, one which is being used
by my mouse.  I have tried swapping them over and the mouse still works.

Any help gratefully received.  Further specific questions are:

1. Where do I find out what the error codes mean?

2. Did I buy the wrong type of external modem?

Regards

Janet