My 2 year contract with AT&T is almost over?

After my contract ends (in november)
i know i get to keep my iphone 4, but it won't have the service anymore.
could i go elsewhere (like sprint) with my iphone 4 and just buy the service and not get another phone?

You can pay by the month afterwards.

Yes you will have service after… ATT will continue to charge you month to month without you signing a new contract. You are simply not bound to stay with them for any length of time after… But people usually want to upgrade phones. I certainly would. AND never go to sprint…

A AT&T phone is GSM and will only work with AT&T and T-Mobile. Sprint and Verizon use CDMA phones.

There are also other prepaid providers that you can use your phone with. But the prepaid providers buy all of their airtime from any of the major networks, AT&T, T-Mobile, Sprint and Verizon.

If you like the terms of your contract and want to keep using your phone with AT&T, just keep paying your bill and you do not have to get a new phone.