T-mo short for Nokia 8801 is silly. T-Mobile doesn't make phones. As for the security code the default is 12345. If you changed it to something else you'll have to contact Nokia and perhaps they can help you.
Yes i am quite aware that they do not make or manufacture phones. It is a T-Mobile "Branded" phone, locked to there network. 12345 doesn't work either. so i hope so one else will read this with the Master Reset code and will help me. thanks