Had issues with my launch day 6s 16gb. Always dropping to No Service and losing calls / data. Had T-Mobile send me a replacement. When it arrived, i was prompted on the iPhone to chose a carrier to lock the phone to. I Chose verizon. I have T-Mobile, but all the phones are the same, and VZ is not allowed to lock phones. If this happens to you in the future, choose Verizon as the carrier, and it will really be unlocked for all GSM providers, as well as will work on Verizon.