Maxcom MM821 User Manual page 17

Hold the red button to switch the phone on or off.
You may see one of the following information after power
on:
SIM card is lost or insert incorrectly；
SIM card is damaged or invalid
If SIM card is available but protected by PIN code, it would
display PIN:
Input PIN code and enter.
Use "erase" to delete.
Attention！
If your SIM card doesn't provide PIN and PUK code, please
contact with your carrier.
Residue time：To mention you how many chances left for
you to input the correct PIN. If it is used up, the mobile
phone would inform you that SIM card is locked. You
should input PUK code to unlock.
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