MPX200 Unblock Code.Please Help!!!

[ugur2]

I have an AT&T Mobile MPX200 Phone.I unlocked a few Mpx200 phones AT&T Before but when I want to unlock this it say me
SIM Failure
The action you are attempting is not supported by the SIM

I red thread about this problem that Dr mobile started.I tried everything has written there.I leave phone powered on with another carrier sim in phone for a night,I tried to write 00000000 for unblock code etc.in the third page of this thread unlocker has written this:

problem is solved sorry to all

1) leave phone powered on with another carrier sim in phone for all night
2) type all 00000000 for unblock code, password, new password
phone get the SIM failure screen which says "the action you are attempting is not supported by this SIM"
3) type NCK in unblock code, password, new password field

phone is unlocked
tested with 3 different MPX200 phone

I tried all of these solution but could not unlock the phone.if anyone got and fix this problem before Please can you write me how to unlock phone step by step.if no one help me I will give back the phone to my customer.

Best Regards.

Ugur