I have an 8520 and I use it with a PAYG sim from Virgin. Periodically it connects itself to the internet (once every week? and several times per day every 30 minutes). I have to pay 30 pence for each day it does this - doesn't sound like a lot of money but it is still money down the drain for an ultra-light user like myself.
Virgin say the reason for this is that the phone is trying to update itself - is this true? More importantly, can I change the settings on the phone to stop it doing this whilst still being able to access the web when I need to?
How to stop phone connecting to internet
