All it takes is replacing the actual phone dialer app (which AFAIK can only be done in AOSP-based distributions) to make it work transparently.
You'd also have to add a phone number broadcasting service to make it work with phone numbers though, but I can see the potential. I'm much more skeptical about range, battery or security concerns.
> You'd also have to add a phone number broadcasting service to make it work with phone numbers though, but I can see the potential. I'm much more skeptical about range, battery or security concerns
Have the app sync to a registry online when connectivity is available, and keep the key-value table locally (phone->deviceID).
Ugh, it's a lot less magical than they make it seem in the video.