-14-
The SIM card
is not in
position.
Check the SIM card
The metal
face of the
SIM card is
polluted.
Clean the SIM card with a clean cloth
Poor received
signal quality
Signals are
obstructed.
For instance,
radio waves
cannot be
effectively
transmitted
nearby a high
building or in
a basement.
Move to a place where signals can be effectively transmitted