Bluephone, a new service from BT, will allow a user to make Voice over IP calls with bluetooth while at home or otherwise in the presence of a bluetooth base station. When they are not near a base station, the phone will switch over to the GSM cellular network. All of this is going to work seamlessly and be totally transparent to the user of course (I’m only being a slightly sarcastic here). Motorola and NEC appear to be working on the same sort of thing using Wi-fi instead of bluetooth.