Yezz BILLY 4.7 Manual Del Usuario página 81

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Insert the SIM card.
Your phone has two SIM card slots allowing you to use two SIM cards and switch
between them.
Repeat these steps for the other side to add a second SIM card.
Without inserting a SIM card, you can use your phone's non-network functions
and access almost all menus.
•
Replace the battery cover