You can prevent unauthorized persons from using your telephone and its electronic notebook during your absence. 

Precondition: You must have configured a personal identification number (PIN) for your telephone . 

To lock and unlock the telephone:

Select and confirm. 

Enter the code for "on" or "off". 

Enter the telephone lock PIN . 

While the telephone is locked, a special dial tone sounds when you lift the handset. You can continue to dial internal numbers as usual.  Your telephone can also be locked or unlocked again by an authorized party .