1-9. OPERATIONAL MODES AND CONTROLS. (CONT)
DC SUPERVISION MODE (CONT)
The seize tone is stopped by the MODE SELECTOR SWITCH which sets the latch circuit when the handset is lifted from the cradle.
The MODE SELECTOR SWITCH is open when in the DC SUPV position, and this removes the input of the timer from hookswitch.
An off cradle indication is given to the switching facility when a load resistor is inserted between the send and receive transformers at
the switching facility. This causes a current drain of 14 ma on the power supply at the switching facility. This current drain is seen as a
request for service or an answer, depending upon whether it is an incoming call to the telephone set or coming from the telephone set
When the handset is replaced on the cradle, the load resistor is removed by way of the hookswitch and the switching facility sees the
on-hook condition due to the reduced current drain.