(2) The tip and ring contacts of the line jacks are connected by wires to terminals on the rear panel of the
switchboard. Since the telephone line from each telephone station is connected to one pair of these terminals, each
telephone station has a direct connection to a line jack on the front panel of the switchboard. Figure 41 shows four
telephone stations (numbers 1001 through 1004), each of which is connected by a separate telephone line to a jack on the
switchboard. Also shown in the figure are two cord circuits, connected through their respective filter networks to the
battery bus bars. All of the cord circuits contained in a switchboard are connected in this manner.
c. Tracing a call through switchboard.
(1) The progress of a call from station 1001 (the calling station) to station 1002 (the called station) through the
switchboard is traced in figure 42. Again, the operation of the signaling and supervisory circuits is not considered in this
introductory simplification. Assume that the operator is informed that station 1001 wishes to place a call. He inserts the
answer plug of cord circuit 1 in the line jack connected to station 1001, in A. This causes the tip and ring contacts of the
plug to make contact with the tip and ring springs of the line jack, as shown.
(2) The operator switches his telephone set into the cord circuit. He receives the number of the called station,
1002, from the calling station, and inserts the call plug of the same cord circuit used in answering the calling station in the
line jack associated with station 1002, as in B. He then rings station 1002 and watches for the answer signal. (This is
made known to the operator by means of the supervisory circuit associated with the cord circuit, as explained later.) When
station 1002 answers the ring, the ringing is stopped.
(3) A talking path now is established between station 1001 and station 1002. The path is from station 1001 over
the tip side of the telephone line to the tip contacts of the associated line jack and the answer cord; through the tip
conductors of the answer and call cords to the tip contacts of the call plug and the line jack of station 1002; over the tip
side of the telephone line of station 1002 to the telephone set of station 1002; over the ring side of the telephone line of
station 1002 to the ring contacts of the associated line jack and the call plug; through the ring conductors of the call and
answer cords to the ring contacts of the answer plug and the line jack of station 1001; and, finally, over the ring side of the
telephone line of station 1001 to the telephone set.