How Does the Caller ID Work?

The Caller ID Appears on the Display When Your Telephone Rings

As your telephone rings, the display shows you the caller’s phone number or name if the name has stored in the Speed-Dial. Once you answer a call, the caller’s ID disappears. You will see up to the first 16 characters of the number on the display.
Note Note
• 
If Out of Area appears on the display, it means that the call came from outside your caller ID service area or a public phone. 1
• 
If Private Call appears on the display, it means the caller intentionally blocked the transmission of his/her ID. 1
1
Depends on network function.