Summary: Plug your phone into this tiny box, register for a free landline number with e.g. sipgate.co.uk, and make and receive calls via the internet just as with your existing bt line. If you have cable broadband (and a mobile for emergencies) you could dispense with your conventional landline altogether. The call quality is good and the device supports voicemail, caller id, call waiting etc. Setup is easy but the supplied cd instructions are poor.