GSM on 3G and 4G Networks
3G (3rd Generation) and 4G (4th Generation) refer to networking standards in cell phone technology capable of providing high-speed data service to mobile devices.
The GSM consoles do not utilize data services of any kind (cellular only). As such, the data speeds of the carrier is unimportant - all that matters is the need for a GSM network.
Out of the biggest US carriers, AT&T and T-Mobile run on GSM networks.
In Canada, the larger carriers that are compatible are Rogers and Fido.
You can find a full list of US GSM carriers here: http://www.unlockedshop.com/a-full-list-of-gsm-carriers-in-the-usa/