Apparently a shoe phone similar to this was a really big deal in some dumb movie or TV show. But now the thing actually exists, using common mobile phone gear and a hollowed-out heel.
Australian Paul Gardner-Stephen originally created his Gen 2 prototype shoe phone for his church group by carving out the heel of a dress shoe and stuffing in parts of a mobile phone, along with a bluetooth headset. As a result, Gardner-Stephen is able to place calls using voice commands, and use a handful of controls using makeshift buttons he created by punching holes in the heel.
The only problem is that Gardner-Stephen says he wants to produce the shoe for the medical industry and help people by using it to relay data from biosensors and other crap. Um, what?! If global
thermonucleardynamic espionage isn't your primary objective with this thing, Mr. Gardner-Stephen, I believe you're missing the point. [Gen 2 Shoe Phone via Instructables via Crave]