Will an Australian Iphone 4s work in New Zealand?

My Nana lives in australia and has an Iphone 4s to give to me. She has used it but need the screen replaced as it was dropped on the bathroom tile floor. But she is getting it replaced for me. I'm not sure where she purchased it from, I do think I will have to get it unlocked because she was on a plan that you pay it off for 24 months. I'm not too sure if it can be and if so where? I would ask her but she doesn't know squat about technology.

The Iphone will work about anywhere. You need to find out from her what carrier she was using and how many months she has left on her contract. If she has had the phone for over 18 to 20 months she could get an upgrade for herself for little to no money and once the old phone is disconnected she can give it to you for free. You would then have to find a carrier for your self or if you live with your parents they may be able to add you to their contract. She can call her carrier to see how much it would cost. If she has insurance will they fix it or will they just replace it allowing her to have the old one repaired.