Nokia 2190 Rejects Cingular SIM

I have four different Nokia 2190's and two are supposed to be unlocked. I use Cingular's service and when I insert the Cingular SIM into the unlocked ones, they reject it. I don't understand that because they accept a T-Mobile SIM and were never on T-Mobile's service originally so would'nt that mean they are unlocked?

Hi, I tried to type in that test code beginning with #pw but it won't let me go from numeric to alpha on the keypad.