Maxis user here...and I had the same problem connecting to 3G mobile internet and fMMS. Tried adjusting the settings and restarting (remove battery and sim) as advised by service provider technician, but still could not get it to work. They tweaked their settings at their end also.

I swap my blackberry sim to my N900 and managed to get connected. So i figured could be the sim card related and requested for a new sim card. Now both the mobile internet and fMMS works!

Go change your sim card! It's free.

By the way, fMMS only works with (Maxis) mobile internet. You'll get MMS notification, but will not be able to download the content without Maxis mobile internet connection.