28
If
your
SIM
card
is
a
prepaid
card,
to
sure
whether
the
card
is
insufficient.
Please
turn
to
your
network
provider,
and
to
sure
whether
to
be
refused
registration
network
by
other
reasons.
Weak
signal
or
no
signal
You
may
be
in
a
location
where
the
reception
is
bad,
such
as
tunnel
or
cellar,
please
relocate
and
try
again.
You
can
try
turning
around
slightly
or
get
near
the
window
if
you
are
in
the
room.
Bad
talking
quality
Weak
signal,
you
can
try
solutions
above
Low
battery,
change
a
new
battery
or
charge
the
battery
Use
up
volume
key
to
adjust
microphone
volume
Can’t
make
a
call
Check
if
you
enter
the
correct
number
and
press
send
key
Check
if
you
set
call
barring,
if
yes
cancel
it
Can’t
receive
calls
Check
if
your
phone
is
turned
on
Check
if
screens
shows
no
signal,
if
yes,
try
solutions
above
Check
if
you
set
call
barring,
if
yes,
cancel
it
Screen
is
dark
Check
if
battery
is
low,
change
a
battery
or
charge
the
battery
Adjust
the
brightness
in
settings
Your
phone
may
be
affected
with
damp,
keep
it
dry
