With the caller ID Blocker installed, your name and phone number will not be displayed on caller ID devices when you make a phone call, your phone number remains private and cannot be displayed without your consent when you make a call, One caller ID Blocker protects all the same-number extentions in your home or office. You can cancel blocking for a specific call by pressing the phones "flash" button or switchhook after you hear the dial tone, before you make a call.