Samsung SF-4500 Service Manual page 112

12-3. Hook Circuit Diagram
Samsung Electronics
OFF_HOOK_STATE
MHS_IN
P1-7
(*)SERIAL_ON
P1-8
MHS_OUT
P1-6
LINE_IN
P1-5
EXT
P1-3
LINE_OUT
P1-4
(*)SERIAL_OFF
P1-9
RING_OUT
P1-2
RING_IN
P1-1
(*) IS FOR ITALY
Schematic Diagrams
12-9