Need help USB modem

[Roger]

A friend of my daughter has converted from windows to Linux just 
yesterday but has a Sierra Aircard 312U wireless USB modem and cannot 
get internet on the laptop.
I've spoent hours googling to no avail. Search shows that this modem is 
useless for Linux so can someone please tell me which wireless usb 
modems work best on all linux flavours, easy to set up, etc.
There's got to be something but I haven't had any luck finding information.
If this change is successful there could follow at least 3 others so I 
really need help here please.
Cheers and thanks in advance
Roger