" Alli wants to know can he use his AT&T phone when he switches to Verizon unfortunately no and though T-Mobile phones will mingle with AT&T and vice versa. AT&T and Verizon however use two different technologies namely GSM and CD MA and they're not compatible with the other. On purpose or not years ago when cellphones when digital different companies chose different standards. You can get answers to your tech questions at 1010wins.com. Just follow the links to tech bytes in the extra section Brett -- 1010 wins."