All recent iPhones and cellular-capable iPads come with SIM (subscribe identity module) card slots on their sides. A SIM card is how your carrier provides all the information your device needs to get on their network and access the voice and data services linked to your account. There may be times when you'll beed to swap the SIM card in your iPhone or iPad. If you upgrade to a new device you'll have to move the SIM card to that new device. If you're traveling and want to use a local SIM to avoid roaming charges, you'll have to swap it in. If something goes wrong with your SIM card you may even need to replace it. Whatever the reason, it's a super simple process and all you need is an Apple SIM-card remover tool or just a plain old paper clip!
What you need to remove the SIM card in your iPhone or iPad
The only thing you need in order to remove the SIM card in your iPhone or iPad is an Apple SIM card remover tool (which comes included in the box in some countries, especially when you buy an unlocked device) or a small bent paperclip.
If you're using a paper clip, straighten the long end until it projects out (see the photo above). If you're using something else, like tip of a small screwdriver, just make sure it fits into the SIM ejector slot. You don't want to mangle your device.
Find where your SIM tray is located on your iPhone or iPad model
Almost every iPhone comes equipped with a SIM card tray. The only exception was the CDMA variant of the iPhone 4. So if you have an iPhone 4s or newer, you have a SIM card slot. Here is where you can find it given your iPhone model:
Original iPhone/iPhone 3G/iPhone 3GS: On the top of the iPhone in between the headphone jack and power button
iPhone 4/4S/5/5s: On the right side of iPhone, the side opposite your mute switch and volume buttons
Only cellular capable iPads have SIM trays. If you have one, here is where you can find your SIM tray:
Original iPad: Along the left side of the iPad towards the middle, opposite the side that contains the mute switch and volume buttons
iPad 2/3/4: Along top left side of the iPad, opposite the side that contains the mute switch and volume buttons
iPad Air: On the bottom right side of the iPad, the same side that contains the mute switch and volume buttons
How to remove the SIM card in an iPhone or iPad
Insert the small paperclip you bent earlier into the small pin hole opening in the SIM tray.
Apply a small amount of pressure until the SIM tray pops out of the iPhone or iPad. Don't apply pressure at an angle, only in the direction of the pin hole.
Grab hold of the SIM tray and pull straight out.
Swap your SIM card and re-insert the tray. Make sure you have installed the SIM in the correct orientation. Also make sure you are inserting the SIM tray in the correct orientation.
Keep in mind that you should never force a SIM tray back in place. You can break pins off the logic board and that can leave your iPhone or iPad unable to connect to any cellular network. Always make sure the SIM is installed in the tray correctly and that you're putting it back in your iPhone or iPad in the correct direction. An easy way to be sure is to line up the pin hole. This way you know you're putting it in correctly.