How to Access the SIM Card in an iPhone

To access or remove the SIM card from an iPhone:
  1. Obtain a paperclip
  2. Straighten the paperclip
  3. Locate the SIM card tray (on the original model. iPhone 2 or 3, it will be on the top. iPhone 4,5, and 6 it is on the side).
  4. Push the paperclip in the release hole in the SIM tray and provide firm pressure until it releases

photo credit: http://www.maclife.com/


After you remove and or replace the SIM card, push the SIM tray back into the phone. Pay careful attention to insert the tray in the same orientation that you removed it as it will only go in one way.

Official support link: https://support.apple.com/en-us/HT201337