About swapping the SIM card
Learn about swapping the SIM card of your iPhone.
At times, you may need to change the SIM card of your iPhone. For example, this is required for iPhone repair, warranty service, or if you own an authorized unlocked phone and want to use a different network provider's SIM.
Note: This information applies to devices that use a SIM card.
When changing the SIM card, power off the device prior to opening the SIM tray. After you have changed the SIM card for your iPhone you may need to reconnect it to iTunes.
iPhone keeps a record of previously inserted SIM cards, but if the carrier name of your SIM does not show up in the status bar after you changed the SIM you will need to reconnect iPhone to iTunes. If you do not connect iPhone to iTunes after changing or reinserting the SIM, iPhone may not work as expected.
If your iPhone does not show up in iTunes (on the left hand side of the iTunes window under Devices), please see the following links for assistance: