Telephone Entry Intercom series telephone entry intercoms are fully surface mount stainless steel faceplate units in a painted enclosure with built-in rain hood. All master stations can be used with 1 to 20 building entrances per system. Built-in (and add-on) alphabetical directory modules make finding the tenant's code very easy, even in larger buildings. by entering a simple 1 to 4 digit code, the system calls the correct phone number, to allow access. The called party's phone number remains secret.