Samsung GSM1800 - Manual (Page 18)

Getting Started
18
3. Slide the SIM card into the SIM card socket, as
shown, so that it locks the card into position.
Make sure the gold contacts of the card face into
the phone.
Note: When you need to remove the SIM card,
slide it upwards, as shown, and take it out of
the socket.
4. Replace the battery so that the tabs on the end
align with the slots at the bottom of the phone.