iPhone 5 IMEI not in carrier's database

[MrMacMack]

Return the phone that was sold to you by your "friend"

It's probably the reason why he sold it to you which should make you question how good of a friend he is.

 

[ogremoustro]

OP isn't trying to use it with a GSM carrier. He wants to use it with T-Mobile.

http://community.sprint.com/baw/message/564751#564751

I'm hearing you two mention "usually" and "probably" -- thus even more reason for OP to call in and inquire.

T-Mobile is a GSM carrier.