I bought the AT&T DECT 6.0 from best buy not too long ago once my old land line died. It comes with 2 handsets (a base with answering service, and additional charger and handset). You can add as many more handsets as you want (I'm sure there is an upper limit...like 10 or 12).
http://telephones.att.com/telephones_ui/phone_store/dsp_product.cfm?itemID=3930&parent=23655
Sure I had to put some gaff tape over all the AT&T Logos, but small price to pay. When I walk in my house, my iphone cuts in automagically and all calls ring through to the home handsets. The only downer is that it pulls the caller ID information and compares it to the internal phonebook, and not the phonebook in your cell phone. If a number is in your phone but not in your AT&T phone it will just show you the number on the ID, and not the name. When I walk out of the house, by the time i'm down the block I'm into normal cell operation again. Haven't had any problems with it at all. Looks sleek too.
Serving coffee on aircraft causes turbulence.