I could not find the C720 anywhere in Canada until I looked on Acer's website and their online store has:
32GB and 2GB RAM (which I ordered)
and the fabled 16GB with 4GB RAM
don't know if the US store has the same
Acer North America Online Store - Chromebooks
Did you cut the sim card into a micro?
I had mine cut and it wasn't working, worked for 5 minutes then lost it, popped it back into my old blackberry and worked
had to go to Wind (my carrier) to get a new micro-sim card