I've seen various threads going around on these modems, and I've been having a fair share of issues.
In 5.16 it would be detected, but have no ports (it uses NDIS and a web front end).
In 5.20 it was detected, and showed up as a USB port (yay! I can add a ppp interface, same for 5.22)
However - No joy in dialling. It has two channels, if I try connect via serial terminal to the first (0) I get nothing back, and if I connect to the second (1) I mostly get nothing. I say mostly as I did at one point receive a bunch of what looked like HTML / HTTP addresses and messages. The entire terminal then started displaying garbage and that was the last I had.
I've tried every combination of Data and Info channels, with no joy on dialling. In serial terminal, I cannot enter keystrokes / ATZ / anything.
Any ideas welcome! I have saved a Supout.rif from a RB751U on 5.16 and a Supout.rif from a RB751UG on 5.22 if it does need to go to support and I'm not doing something monumentally silly.