What will happen if i put a sim card from my regular phone to an iphone?

I have a pantech jest and bought and iphone from my friend and wanted to know what will happen if i take the sim from my jest and put it in my iphone. I have verizon

If the iphone is locked to a carrier that isn't verizon)
>the iphone won't work (not as a phone anyway)

if the iphone is locked to verizon:
>the iphone should work just fine as a phone

if the iphone is unlocked
>the iphone should work just fine regardless of what carrier sim you put into it

***also note the iphone4 and above (4. 4S, 5) require a micro-sim and not the regular fat sim.

Nothing because Verizon doesn't use SIM cards. It would only work on Verizon if it were a Verizon iPhone.