Im wondering whether or not to submit a new bug for this but i went over that bug report and i saw no mention of numbers starting with #.

As of now, it says 'incorrect number" when trying to send #225# (#BAL#) for example.

For T-Mobile USA, the carrier allows you to send these codes to get quick account info

#BAL# - Balance on the accound
#MIN# - Minutes used for your pay period
#MSG# - Messages sent/left for your pay period

These are just some but they greatly come in handy and a quick way to check so i wont get any overage chages. Its sad they dont work on the n900.