What I need to do is import 4 digit extensions with users. This is ok with [0-9][0-9][0-9][0-9]$ so I go from 99112222 --to 2222 no issues.
what i need to do is change one of the numbers the first 2 and change it to a 9 so I end up with 9222not 2222
how do I write this reg exp
I don't believe this is possible with Unity Connection's relatively limited support of regular expressions. You'd need to combine two regular expressions, to take the first digit (if that will always be 9), and then the last four, which you can't do.
You may be able to use the Bulk Administration Tool so that you can modify the CSV file to get the correct phone numbers.