Zte ZT303 User Manual page 120

Some network operators can't provide such service, for
detailed information, please contact with local network
operator. Network operators provide "Barring Code"
with four numbers so that you can activate "Barring
Code". In this menu, you can restrict the following
callings respectively.
Outgoing Calls It may Activate, Deactivate,
Incoming Calls It may activate, deactivate,
Cancel All
Change Barring PW
or Query three operations for
barring calls such as "All Calls,
International Calls,
International except
Once all outgoing calls are
barring, the device can not dial
any numbers except emergent
number.
query "All Calls" barring, namely
prohibit all the incoming calls; or
activate, deactivate, query all the
roaming incoming calls.
Input the barring password
which makes all call barring
invalid
Input the old call
114
and
Home".