I didn't even know thats how it works in America. The phone you buy with your own money can only be used at the carrier you original bought it from. So if you wanted to change carriers because you found a better deal elsewhere, you'd also have to buy a new phone? Thank god we don't have this in Canada. Switched carriers a few months back and it was a seamless experience. Took the old SIM card out and popped a new one it. Thats it. My iPhone 11 wasn't even paid off. Was even able to keep the same number.