AT&T Door Phone Controller - Manual (Page 46)

As an alternative response when the telephone or door
bell/chime is heard, the person inside the building can press
the door-unlock push button, which will stop the ringing and will
open the door. This allows the door to be unlatched without the
use of a phone.
Calling the Door Speaker from Inside the Building
To initiate a call to the door, the person within the building
simply takes the telephone off-hook and hook-flashes the
telephone within the first 4 seconds. At this point, there will be
direct two-way communication from within the building to the
door speaker.
Telephone Line In Use When Visitor Presses Door
Speaker Button
Once the push button is
pressed, you can “Hook Flash”
to the door speaker and then
back to the original call only
once, unless the push button is
pressed again.
If you forget to hook-flash back
to the original call, the AT&T
Door Phone Controller will call
you back.
If a visitor presses the door speaker button while an existing
call is already taking place on the C.O. line, the AT&T Door
Phone Controller will generate a “door alert” signal to indicate
a visitor needs attention at the entrance. The person inside the
building can hook-flash the phone and be in direct two-way
communication to the door speaker. Then normal AT&T Door
Phone Controller functions can take place. When door phone
functions have been completed, i.e., door has been remotely
opened, hook-flashing the phone again within the forced
disconnect timeout (or pressing 9) will return the line back to
the original call. This feature operates much like a call-waiting
function.
3-8 Installation — Home/Residential