The SIM card in the iPhone is removable, but it’s hidden. To remove the SIM card, you need the sim card removal tool that came with your iPhone.
1. Locate the SIM Card Slot
The slot is located at the top of the iPhone, between the headphone jack and the power button.
2. Open the Slot
Take your removal tool and insert it into the little hole. Then firmly push down until the slot pops up, as shown below.
The SIM card is in a cradle. You can pop the card out of the cradle. To replace the SIM card, put the card back in the cradle. The cradle and card are notched in a way that forces you to replace the card on the proper side. Then just slide the card back into the iPhone.