"As Google Glass doesn’t have a mobile antenna or GPS tracking, My Glass is essential if you want to send and receive SMS from Google Glass, use a data connection, or navigate using GPS."

The phone is pretty much essential. NB: My Glass is the companion Android app.

http://www.androidauthority.com/how-it-works-google-glass-19...

The Glass device is way too small for a battery that could power a 3G or LTE radio.