Android phones, apps and tablets

All the watches seem to follow the Google Glass line... they are handsets, remote displays, and a few additional sensors... but they all seem to require a smartphone to be the modem/hub and main connectivity.

I'm looking for the opposite of that.

For a very small, long battery, modem/hub of connectivity, but no display or sensors... just a pure communications device.

afaik there was an attempt to do this. Exactly like the Star Trek communicator (NG version not the old school one). No idea wtf happened to it though