Technology began to play a part in the construction of shoes in the early 50s with the development of the stiletto heel
using a thin spike of metal to obtain ulitmate slimness.
By the end of the 60s heels came in all shapes or famously there were shoes with no heels at all but none of them went so far as
Maxwell Smart's shoe phone.
Get Smart satirised the TV spy genre, itself set off by the success of the Bond films. No self respecting TV spy was without his homing transmitter hidden in the heel of his shoe (or suicide pill). Needless to say the shoe was only worn when the story called for Smart to answer the phone, like James Bond's cars overloaded with guns, ejector seats, rocket launchers and oil slicks, there was no room for the engine - or foot. However Smart's main problem with the device was getting the operator to put him through.
Agent 86 Maxwell Smart
Maxwell receives a call - YouTube