These Sims will work on any unlocked AT&T and T-mobile phones. Even iPhone users can jump ship because a mini Sim-card will also be available for iPhone users. (You need a unlocked/jailbroken iPhone).
Why choose prepaid?
* No activation fee
* No commitment (2 year contract) besides the 30 days you already paid
* You can port your old numbers
* You can even sign up for automatic refills
I get a lot of "friends" that keep on asking me to co-sign for them for a 2-year contract using my Credit. I made that mistake once! Will never do it again. Now I just tell them to go for prepaid. Heck, I just dropped my AT&T plan for it. And I've been with AT&T since 2003.
You can purchase the Sim-Cards here. straighttalksim
Maybe now AT&T will stop price gouging their customers! If not, they can all jump ship.
T-Mobile also has some great pre-paid plans. Including a $50 a month unlimited date, talk and web plan and a $30 plan which is great for your kids. 1500 talk and text and 30mb web.
T-Mobile also have a value plan which is also a great deal. However, you do have to be in a 2year commitment and pay an activation fee.