No Career Name after battery replacement

I just tried to replace my battery on my iphone 4. I got through it pretty easily. But then When I go to turn my phone on, I see no carrier name (i do have my iphone factory unlocked for tmobile, but I don't think that that should make a difference). So I send a text and it goes through, (but at a slow speed), and when I try a call, the phone I am calling rings, they answer, and my phone just says "calling" still! I also don't hear a ring through my ear piece.