Q: how to set up iphone 3gs (no phone service desired)

Having problems setting up iphone 3gs

AT&T gave me an old sim card(no service provided)

This phone is gift from neighbor

phone does recognize my router and allowed me to put in my password- so I have wifi and that is all I have

it says contact apple customer support

when I plug into computer it recognizes phone (with old owners name) and says the phone has a problem

apple says I can chat, yet I have yet to have that chat work