Caller Line Identification displays on a (2×16) LCD the phone number of the person who is ringing you, before you even answer. Even though most modern phones have this option built-in it’s nice to learn how this things works and who knows it might even be usefull when you try to integrate such a function in a future project. The number stays on the LCD till its replaced by a new received phone number OR if the button is pressed.
The circuit has allot more functions, but I’m not gonna present them here, just visit it’s page to see the full info.
Caller Line Identification: [Link]