When fixed dialling is turned on, you can only call selected numbers and do emergency calls. Incoming calls aren't affected.
Press the menu icon.
Press Additional settings.
Press Fixed Dialling Numbers.
Press Enable FDN to turn on fixed dialling.
Key in your PIN2 and press OK. The default PIN2 is 0000.
Press Disable FDN to turn off fixed dialling.
Press the Home key to return to the home screen.