Just bought a siemens gigaset one for use with my phone. I replaced my land line with my cell phone, so this is a useful little device.

The gigaset one will pair 3 devices via bluetooth. It then connects to your normal phone. If you have a base station with 2-3 wireless extensions, you can attach the base station and let it do all of the hard work.

This devices allows for your landline phones to operate has headsets to your pre over BT. I can actually place calls from either the phone or the landline (not connected to a PBX, just in house) handsets over my cellular connection. The volume is sufficient if not a little low. I can dial from the landline. The device is extremely easy to setup (1 button to push per phone on the gigaset, pairing as usual on the phone). The gigaset reconnects when the phone is in range (claims 10 ft, but I get about 15-20 ft and no issues). The land line has the exact same caller id capabilities that the cellphone has (usually based off of the contacts list on the cellphone).

All in all, if you replaced your landline with a cell phone but would still like to use the landline at the house, this device is a good deal. It ran 75 dollars and it works perfectly. I use it with a base station and 2 extension wireless handsets. I can use my cell phone anywhere in the house now without ever unplugging it from the charger (or off a touchstone). I don't have to go running across the house to answer it (I have the extension handsets in every bedroom), and I can actually hear it ring everywhere in the house (through the wireless handsets). I can also use the built in address book on the wireless handsets to dial.