My bad guys, I wasn't trying to sound rude, but here are two methods to check if a T-mobile Phone is blacklisted:

1. Go to a t-mobile store and ask them if they would check if the phone is blacklisted.
2. Buy a prepaid sim card (.99 cents on t-mobiles website). Activate the sim-card by calling, eventually a machine will ask you to enter your imei. If the imei is clean, it will let you proceed. However if the imei is bad, it will tell you the imei has been blocked. Once it tells you that your imei is blocked you can hang up and your sim card won't be activated. I think you can do this as many times as you want.