I was talking to my dad about how it works since I'm switching from verizon to AT&T, obviously. He said I wouldn't have to cancel my verizon (I am on a family plan) til after I get the iphone and activate my AT&T plan, but I don't understand how that is possible especially if I want to use the same number. Do I need to cancel my Verizon plan beforehand or can I really activate an AT&T plan and then cancel while still having the same number?