Can I use a Verizon iPhone 4s on AT&T?

If i get a Verizon iPhone 4s and unlock it can I use it with AT&T?

Yes aslong as you unlock you just need a SIM card

No.AT&T and Verizon use incompatible radio communication formats… In other words, the hardware inside a Verizon iPhone is different from what's inside an AT&T iPhone; Verizon uses CDMA and AT&T uses GSM. No Verizon phone* will ever work on AT&T and vice-versa.

(Some Verizon phones are global and do have GSM capability, maybe even the iPhone. But the GSM in those phones is intentionally designed to NOT be compatible with AT&T GSM).

Isaiah Young is correct
Pearls Before Swine is wrong

the iPhone 4s is a WORLD PHONE capable of being on any CDMA or GSM network
you will need to get the phone unlocked, but then you can install an AT&T SIM card and activate it on AT&T's network.

Yes you can but first you will have to unlock it at places like unlockatt.com its legall i did mine there it worked

Should be able to yes.

Yes you can if you unlock it.