Can I use iPhone 5 from verizon not unlocked! With AT&T?

I have Verizon iPhone 5.bought it 1 week ago.

can i use this phone using AT&T Sim card?

The phone is not Unlocked! Just got it from verizon

Actually, all Verizon iPhone 5's are unlocked from the start.

So it *will* work with an AT&T SIM card, but the data will only be 3G, not 4G.

No you can't use it until unlocking or jailbroken.

The Verizon iPhone 5 was sold unlocked, so yes it is in fact unlocked, so you should be able to use it with an AT&T SIM but make note that obviously doesn't mean that the Verizon payments automatically stop.