LG G8000 User Manual page 216

Use this function to restrict usage of the phone with numbers that
belong to certain user groups. When this function is used every
outgoing call is associated with a group index. If a group index is
specified, it is used for all outgoing calls. If no group index is
specified, the network will use the preferential index (a specific index
that is stored in the network).
Setting the selected CUG Index.
Set CUG Index.
Cancel CUG function.
Allows you to change PIN Code, PIN2 Code, Security code, and
Barring password.
PIN is an abbreviation of Personal Identification Number, used to
prevent use by any unauthorised person.
Select
O
[OK] key.
Enter the current PIN/ PIN2 code. If you input the wrong code
more than 3 times, you must enter PUK/ PUK2 code to unblock
the PIN.
If you enter the PUK/PUK2 codes incorrectly more than 10
times, the phone will be blocked and you will need to contacts
your service provider.
Correct entry of your PIN Code will allow you to change your
existing PIN Code.
from the Security Setting List, then press
99