Step 1 — SIM Card

Apple includes a "SIM eject tool" with the iPhone 3G. If you don't have this tool, don't worry, an ordinary paperclip works just as well.

Insert your SIM eject tool or a paper clip into the hole next to the headphone jack.

Press down on the tool until the SIM card tray pops out.

Step 2

Remove the SIM card from the SIM card tray.

The cut-off corner should make it easy to reinstall the SIM card in the correct orientation.