How can activate an iphone with no sim card?

Ok, so i purchased an iphone 6s from a guy that goes to my school. He said that the phone has no sim card. I thought that with no sim card you can just use it like an ipod, and you just won't have service. Turns out the iphone was reset or somthing and i can't get past the "no sim card" screen. I choose my language, region, and connect to Wi-Fi, then it says no sim card. What am i supposed to do? How do i find out what carrier the iphone is connected to? Is it stolen? Anything will help!

Sorry. The only way you'll ever get passed the no sim screen is if you insert a sim in the phone. Ask your friend who bought it from what carrier the phone is on then get a sim from that carrier

The iPhone probably isn't activated. There might be ways to activate it without one, but from my knowledge, you must use the emergency call feature or iTunes. You can google it as I don't know the full instructions as I own only android devices.

Try setting it to airplane mode.

Put a SIM in it.
It only has to be just for a few minutes to finish the activation sequence then you can take it out again.

After the SIM is in, it will go through the actual activation sequence and that's when you find out if it has an icloud lock on it.

If it has, the previous owner needs to unlock it. If they can't or make excuses, it's stolen and it is impossible to do anything with it.
In that case get your money back, with threats of making a police complaint for them selling stolen property if you need to.

The only thing you can legally do with a stolen item is take it to the police; selling it is a criminal offence.
(And "finding" something and not returning it is still criminal theft, if that's how they claim they got it).