The history of electrical handshakes should be traced back to the beginning of the phone. When the phone was invented, only a long enough wire was needed, plus two phones at the end, so that two people far apart could have a voice conversation.
After the number of phones increases, it is necessary for each person who has the phone to communicate with each other. It is impossible for us to pull a line between every two phones. So people set up a telephone office, and each telephone user connected a line to a large circuit board of the telephone office. When A wants to talk to B, he asks the operator of the telephone office to turn on the telephone of B. The operator uses a wire, one end is inserted into the hole of A to the circuit board, and the other end is inserted into the hole of B. This is the "connection", which is equivalent to temporarily pulling a telephone line to A and B, then both parties can The call is over. When the call is completed, the operator removes the wire, which is the “disconnection”. The whole process is "manual exchange", which is actually a process of "closing the switch" and "opening the switch". Therefore, translating "exchange" into "switch" is technically easier to understand.