1. Remove the cover from the front of the Doro 824C.
2. Using your thumb or finger, lift up the back cover using the small notch at the bottom-left of the phone.
3. If the battery is already in the phone, you need to remove it before inserting the SIM card. Using your thumb or finger, lift up the battery via the small notch at the top of the battery compartment.
4. With the metal contacts facing down, slide the SIM card into the SIM card slot.
5. Line up the gold contacts on the battery with the contacts on the phone. Insert the bottom part of the battery first, then push it into place.