Iphone 4s unlock or locked confusion

Hi. I'm buying an iphone 4s off my friend on monday to just use it as an ipod and not as a phone because i don't call so i need it just as an ipod. He is saying that it is locked and now i don't know what that will do? Will it let me use the phone normally or will it do something? Do i have to get it unlocked if i want to use it as an ipod type or something or can i still use it normally with it being locked?

Hi, if it is locked it will not accept any SIM card except the original one it was bought with. What the unlock does is that you can use it with any carrier you want. So it is then fully functional all over the globe.