Robert has iPhone 6 Plus and his wife has iPhone 6. They both want to get iPhone 7. Leo says the time is right to upgrade, especially if he wants the dual camera array of the iPhone 7 Plus. Right now the waiting time is about 6 weeks, so he'll be looking at November. There's two different ways to buy it at Apple, online and at the store. He could also get it from his carrier. Apple will verify his account and if he is financing the phone through the carrier (like with AT&Ts NEXT program), they will give him a phone locked to that carrier. T-Mobile, however, doesn't lock their phones, and Verizon can't lock them because they're under a consent decree. Once Robert has had his phone for awhile and is in good standing, they can unlock it on request. If he buys the phone outright, however, it should come unlocked out of the box.
The interesting thing is that next year will be the tenth anniversary iPhone, and it's bound to be an amazing upgrade.