i have a phone that was recently on a service plan. the service has ended. can it be used as a pay as you go phone?

Can a GoPhone be used on a regular post paid account?

Hi, Let me give you the background of my problem 1. I was added as an add on line to my friend and I am currently using this line for past 12 months as post paid account.2. On 24th Nov 2014 we went to AT&T store near Metro Center and both of us wanted to switch the account to Pre Paid (Pay as you go

I already have a new phone and postpaid service with AT&T. When my 2 year contract is up, will I have to have another credit check to sign for another 2 years? What if I want to get a new phone every year, will I need another credit check?