Wirelss IP telephony
You will be envolved with Wi Max technology and Gatekeeper registration using whatever protocol you find suitable and autoprovision for this devices, Wireless IP telephony is diferent than cellular telephony because it is based on IP protocol over Wireless transport that is very common today, all metro areas will be covered by huge Hot Spots of Wi Max and you will be able to use your ip device from any Endpoing, your car system, your jacket phone 😉 things like that.
At this point the huge problem for size of equipment is the way we input data (FINGERS) so in the future I asume there will be brain inplants interfacing with wireless devices to control everything that is wireless, seems futuristic but you will remember this in 20 years.