You’ll need to have the SIM removal tool that came with your unit or a straightened paper clip.
Straighten the long end of the paper clip until it projects outward.
Look at the side of your iPhone and locate the SIM tray.
If your iPhone is in a case, you’ll need to remove it to locate the SIM tray.
Gently insert the paper clip into the small pinhole opening.
Apply gentle and even pressure inside the hole until the SIM tray pops out.
Pull the SIM tray out of your iPhone.
Take the old SIM card out of the SIM tray and place the new one into the tray.
A small notch indicates how the SIM card is placed.
It will only fit one way.
Don’t force it.
Reinsert the tray the same way it came out.
Here are some things to keep in mind and steps you might try next.
