How to Check Your iPhone's ICCID

Open your iPhone’s Settings. It's an app with gray cogs usually found on your home screen, but you may find it in a folder labeled “Utilities.”

Tap General.

Tap About. This will display a table with various information about your phone.

Find “ICCID" in the table. The SIM number is to the right of it. Knowing your ICCID allows you to check the SIM card's compatibility to another device you want to switch to. If it isn't compatible, you will have to get a new SIM card. Your ICCID can also be used to track your phone, unless the SIM card is removed.