Have you looked developments with FMC (fixed to Mobile Communications?)  FMC uses a dual band mobile technology that allows a users mobile to seamlessly switch a call from their mobile service provider to their home wireless IP network or other wirless hotspots.  Its predicted that as this type of technology grows many people will not bother using a land line.  T-Mobile, is just one of the international companies going down this track, check out their site http://www.theonlyphoneyouneed.com/  and you will see what I mean.