Help Disabling mobile network doesnt disconnect me from net


I canot seem to get my HTC Salsa to disconnect from the internet.

Neither turning the Mobile network off in the settings menu in wireless or using the widget seem to work. I have also set data roaming off, and disabled always-on mobile data but these do not work either.

Aeroplane mode works, but obviously disconnects the phone entirely, so I cannot get calls or messages either.

Is this operator error, something wierd my carrier has done, is my phone not working properly?