I'm wanting to know what carrier, if any, an iphone is locked to?

I'm wanting to know what carrier, if any, an iphone is locked to? - 1

Could be any one of hundreds worldwide or none at all.

Most of them are locked to AT&T. But it could be any.

Whatever carrier is selling that iPhone. The iPhones are sold by 100s of carriers worldwide & of course they would sell them locked to that network.

Of course iPhones are also sold unlocked, so no carrier there.

Try two different carrier SIM cards. That'll tell you if it's unlocked.

If you have access to the phone (you know the password or it doesn't have one), go to the settings menu - it'll tell you which carrier it's with.