How to Lock Phone Numbers
Locked contacts cannot be deleted. This is a convenient way to ensure important contacts are not lost accidentally or by pushing the wrong button. You can edit the contact settings and unlock a contact with the lock code. Locking a contact will not keep it on your phone if all the information is wiped off through a master reset, but it will keep them safe if someone tries to delete your list from the contact menu.
Press the "OK" or "Menu" button to access your phone's main menu.
Scroll to the "Contacts" menu. On many phones, you will use the arrow keys to scroll. Press "OK" or tap on the "Contacts" option. You may need to select "Contact List" to view it on your phone.
Select the "Options" menu. It is usually in a lower corner of your screen. Access from non-touch screen phones by pressing the soft key associated with the appropriate corner.
Scroll to and select "Manage Contacts" by highlighting it and pressing "OK."
Choose "Lock." This will launch a new page with your contacts on it.
Scroll through your contacts. Press "OK" to select those you want to lock. To lock all of your contacts, select the "Mark All" option.
Press "Done." Your selected contacts are now locked. The only way to unlock a contact is by entering your phone's lock code.