Here is a link to setting specific to Telstra (Australia) http://iphone.fibre.net.au/
And if your an optus/Virgin customer – use this profile http://weave.zarack.com/OptusTetherv1.mobileconfig
Just browse to the URL you need on your iphone and it will download/install the relevent profile.
Ps. Don’t forget to turn off wifi to get tethering to work.