Caller ID with Phone Ring Controller Block unwanted calls-you can block certain calls let all other pass or block all others, let certain call pass. Normal Caller ID box let phone ring for all. This unit will ring only to who you want talk to. Store up to 270 phone numbers &amp; names in A-Important 100, B-Normal 100, and R-Reject 70. Easy to set up: List R-black list, and List A, B- white list, hourly control your phone. Large 4- line backlight LCD, easy to read &amp; your phone book directly connect to phone and speed dial.