Just a quick thought any default settings that the system has might need to be changed...Or personal details ..might be a mistake somewhere..?
Or Check with BT to do a line check...Or Check that the Modem is capable of handlng 2MB some are'nt.?
If power is on to modem check for updated drivers..?
Check that your USB controler is updated with latest drivers
If USB Connection try another socket incase you have a dodgy port.
Check in bios that all USB are enabled.
Hope this gives you a hand