Unlocked iPhone 4 But NO SERVICE

Here's my specs…
iPhone 4 (AT&T) - 16GB
iOS @ 5.1.1
Untethered Jailbreak
I brought my iPhone 4 to my favorite Unlocker and he "Factory Unlocked" my iPhone 4. I picked it up the next day, and I inserted my T-Mobile SIM Card (which size IS correct) and the iPhone says "No Service". I hear many things such as restoring the iPhone and such, but wouldn't that ruin the jailbreak and get rid of the unlock?
If you know what to do, can you please tell me with a good description?
By the way, I'm at Baseband: 04.12.01

Ask them. They unlocked my iphone
http://unlockappledevices.com