Mobile as a modem?

I have a sony erricson k850i and i tried to use it as a modem by connecting it by blue tooth. However when i get to the user and password part of the bluetooth set up new device it doesnt allow me to enter the details of my network provider! Has anyone else tried this?

I also tried setting up bluetooth Pan and reg networks to connect and it has problems using the mobile as a device? Any help please! thanks

Check out Howardforums.com. Lots of info there for what you want todo

Should be doable, I always used my old Nokia for this prior to buying an iPhone