Use your iPhone as a modem
Use your iPhone as a 3G modem with your computer
With the iPhone 3.0 update you can now use your iPhone as a 3G modem for your laptop by a process known as 'tethering'. This enables your computer to access the internet via your iPhone's cellular data connection.
To enable tethering you have to contact your mobile phone operator: in the UK O2 charges £15 per month for tethering - and that only allows you to download up to 3GB of data.
Once your operator has enabled tethering you need to click on Settings then General and then click on Network. Now click on Internet Tethering and switch it on.
You can connect your laptop to the iPhone by the USB cable or wirelessly via Bluetooth. The iPhone connection will be listed as an ethernet adapter (En4) connection. Remember to switch tethering off when you have finished.