So every once in a while Apple will (at least in the US) chose to launch a new iPhone with only a certain carrier selection and no SIM-free option. Are such iPhones locked to the carrier you select or do they merely come with that carrier’s SIM? Could you just as well toss that included SIM and replace it with any other SIM you might already have?
It depends on which carrier you choose; I think it’s still true that if you get the GSM phone, (AT&T or T-Mobile), that also has CDMA (Verizon or T-Mobile) — or is it the reverse?; as long as your pay cash for it, or buy it out and are not on the contract, you can Jump through the hoops to get the carrier to unlock the phone, prior to your putting in another carrier’s SIM. You will have to check the model numbers to see exactly which phone goes with which carrier, and then compare that model number two the universal unlocked model. It’s usually number like a A1275 or something. I have no problem taking an old T-Mobile phone and moving it to Ting, and I was able to use the same phone on either CDMA or GSM as I preferred.
I don’t know about other carriers, but Verizon recently has started sim locking all Verizon phones, including iPhones, but they are automatically unlocked about a day after they are activated with a valid postpaid Verizon sim. It used to be that you could purchase a Verizon iPhone and it would be like buying a sim free model, but that is no longer the case (or, it is after the phone has been activated.) Verizon says that they made this change in order to help reduce loss from devices stolen from delivery trucks and store displays and stockrooms.