Originally Posted by Guess
I think you are missing a service book that has to do with SMS. Tmobile will proabably send it down, once they answer your support ticket.
If I am not mistaken there is NO servicebook for SMS, sounds more like a missing or corrupt SMSC.
Go to options, SMS and check the number in Service Center. For T-mobile is has to be +12063130004, also make sure it's set to send over GSM.
Hope this helps.