problem with regexp

Hi everybody,
I'm looking for a regular expression that matches strings like this:

12345678910AA

for the 'numeric block' the best way to write this is: 
\d{11}

but, for the 'alphabetical block' there's a 'little'(?) problem...
this block must not be equals to IT, 
so that the regExp must matches 11111111111II or 11111111111NT
but not 11111111111IT

there are someone that can help me to solve this problem?

thanks a lot
Celestino