I found an iPhone 5 for t-mobile, i already own t-mobile, can i use it by placing a new sim card into it and transferring my line over? What if its reported lost or stolen? Will they deny me from using the phone?
If its reported stolen or lost, the phone is blacklisted and you won't be able to use it. If it hasn't been reported yet, you might still have a chance to connect that iPhone to your account. It will bother your conscience realizing that the owner is trying to find their iPhone and you just made it yours. And you can put your SIM card into the phone but that person can go online and check the IMEI number of the lost phone and see the new number of the iPhone via your SIM. And that person can go to the police and they'll come after you when they find YOUR phone number. So it's very risky and I doubt you'll be able to use that phone. Please do the right thing and try to return it. What would you do if someone STOLE your phone and tried to connect it with their line.