BenQ M315 - Manual (Page 103)

Menus 91
Service Tone
Used to set whether the phone will sound when it detects an
available network.
Security
You can use a PIN code, phone password, and SIM card lock
authentication to prevent unauthorized use of the phone.
PIN Code
A PIN (Personal Identification Number) code is a password
provided by a network operator. When PIN code authentication is
activated, it will prevent unauthorized use of the SIM card. Unless
the correct PIN code is entered when the phone is turned on, the
SIM card cannot be used, even if it is inserted in another phone.
PIN Code
Used to activate/deactivate or change the PIN Code. Before
changing settings for the PIN Code feature, the previously set
PIN Code must be entered.
If you wish to change the PIN Code, you must press in the
Enable item to select On, so that you will be able to enter and
confirm the new password.
PIN2 Code
Used to change the PIN2 code. The procedure is the same as for
the PIN Code.
If the PIN code is entered incorrectly three consecutive times,
this will cause the SIM card to lock down, and a PUK1 code
provided by the network operator will be required to unlock it.
After unlocking, the PIN code will be automatically set to activate
once the phone is turned on.