LG C710h Mode D'emploi page 15

5 Carefully slide the SIM card into the SIM card socket as shown
in the image below. Make sure that the card's gold contacts face
downwards into the phone and that the upper-left angled corner
of the card is positioned, as shown.
Important: The SIM card and its contacts information can be easily
damaged by scratching or bending, so be careful when handling,
inserting, or removing the card. Keep all SIM cards out of reach of
small children.
Note: If the card is not inserted correctly, the phone will not detect
the SIM card.