Allows visitor to enter 1 to 3 digits on the Touch Tone phone located in entry way then dials the associated apartment * After conversing with the visitor, the renter can " Buzz" the visitor in by dialing 1 or 2 digits on their Touch Tone telephone. The dialer provides an adjustable timed relay closure for door openers or strikes. Compatible with Visijng's vandal resistant K-1700-3, K-1900-8 or any Touch Tone Phone.