I own one of those USB modems. If I had a 3G phone I could just move the SIM card from the USB modem to the phone, with no extra cost (provided that I didn't already have a contract for the phone, of course).. the possibility of moving the SIM card to a phone is even mentioned in the carrier papers I got with the USB modem. I'm not in the UK though, if that makes a difference. However, I can't see any _technical_ problems with just moving the SIM card to a phone.