3GS jailbroken/unlocked - can't get on DATA network
i bought a used 3GS that was factory locked to provider A. When I first connected to iTunes, I put in a SIM from provider A just to be able to get passed the unsupported SIM message and into the home screen. I then proceeded to jailbreakme and ultrasn0w unlock.
Now my SIM (from provider B) works well for voice calls but I can't get on the DATA network. 3G and Edge both fail. What's strange is in Settings-General-About, "Network" and "Line" show provider B but at "Carrier", it still lists provider A with a version number.
I am on 4.0.1 with baseband 05.13.04
Any ideas on what I did wrong and what I should do to fix this?