Hopefully someone more knowledgeable will come along.
Since this phone uses CDMA cellular technology, that excludes being able to use it with AT&T and T-Mobile.
I believe that about all that this phone would be compatible with are prepaid phone service providers that use Verizon's network.
e.g., Page Plushttp://www.howardforums.com/forumdisplay.php/364-Page-Plus-Cellular
As far as being able to use the phone with another postpaid plan from another CDMA cellular service provider like Sprint, I think the Reality would have to be offered by that company because I think you would need the firmware from that phone so that you can overwrite your Verizon Reality's firmware with it so that it can be compatible with Sprint.