service provider didn't change these codes,
you should change them:
Find it: Press a > w Settings > Security
> New Passwords
You can also change your SIM PIN codes or
call barring password.
If you forget your unlock code: At the
Enter Unlock Code prompt, try entering 1234 or the
last four digits of your phone number. If that
doesn't work, press a and enter your
six-digit security code instead.
If you forget other codes: If you forget your
security code, SIM PIN code, PIN2 code, or
call barring password, contact your service
provider.
52
basics
lock & unlock phone
You can lock your phone to keep others from
using it. To lock or unlock your phone, you
need the four-digit unlock code.
To manually lock your phone: Press
a > w Settings > Security > Phone Lock > Lock Now.
To automatically lock your phone whenever
you turn it off: Press a > w Settings > Security
> Phone Lock > Automatic Lock > On.
Note: You can make emergency calls on a
locked phone (for more information, see
page 61). A locked phone still rings or vibrates
for incoming calls or messages, but you
need to unlock it to answer.