Q: So whats the difference? Can't I just buy a 2GIG Vivint cell module for my Go!Control panel?

A: No.
Vivint cell modules are locked to them and cannot be used with any other provider or dealer- even if brand new in the box, never opened. You see a lot of these APX/Vivint 2G GSM, and 3G modules being sold on eBay for example.

Ideally you want a module that is unregistered and unlocked. This means it can be used by anyone. Once a module is registered, it then becomes locked to that provider/dealer and cannot be used by another until it is unregistered/released. in Vivint's case, they will never unregister or release a locked module.

These are the Modules to steer clear of:
GSM3 (Rogers)

* notice all of the Vivint modules above are odd numbers, regular modules are even numbered ...GSM2, GSM4, GSM6. Further note: all 2G GSM modules are discontinued, and can no longer be used to activate a new alarm.com account

GC3GR-V (Rogers HSPA)

* notice all the 3G modules above end in "V", regular 3G modules end in "A" (sometimes, this is an "N" after the 'A' or 'V').

Vivint Verizon CDMA GCCDMV-"VN"
Click image for larger version. 

Name:	_20150123_145903.jpg 
Views:	187 
Size:	30.1 KB 
ID:	89

So, how do you know if your module is good to use, is unlocked and unregistered? Alarm.com has a way to check the modules.

You can use module checker freely available to all, and you can access it here: alarm.com cellular module checker

Don't know where to get the modules? See: http://www.2gigforum.com/threads/4-3...llular-modules