Zte R621J User Manual page 23

4. Hold your SIM card with the cut corner oriented as shown and then
slide it into the card holder with the metal contacts facing downward.
SIM card (Subscriber Identity Module) is a micro-chip that holds your
personal information such as names and phone numbers. Your phone
won't work without it. If you already have contacts on your SIM card,
they can be transferred in most cases.
5. Insert the memory card with the metal contacts facing down until it
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