Q: Is it known whether customers can walk into an Apple Store and buy a full-priced and unlocked phone or will all September 21st sales be through carriers and with a contract? - Adam A: This will vary from country to country. Initially in the U.S., Apple Stores will only be selling the iPhone 5 on contract for all of the three supported carriers—AT&T, Verizon and Sprint—with the sale of unlocked, contract-free phones to become available…