Telephone exchange

The telephone was useless without a network. Bell's invention could transmit voice over wires, but each conversation required a dedicated line between two specific locations. A business owner wanting to reach ten different parties would need ten separate telephone lines. The number of wires required grew with the square of the participants—for a hundred subscribers to reach each other directly, nearly five thousand separate circuits would be needed. The telephone, as initially conceived, could not scale.

Tivadar Puskás, a Hungarian inventor working with Edison, proposed the solution: a central switching point where all lines converged and could be temporarily connected to each other. Instead of a dedicated line for each possible pair of subscribers, each telephone needed only a single line to the exchange. An operator at the exchange would receive a call, ask who the caller wanted to reach, and physically connect the two lines by plugging a cord between their jacks on a switchboard. The connection lasted only for the duration of the call, then was broken so the lines could be used for other conversations.

The first commercial telephone exchange opened in New Haven, Connecticut, on January 28, 1878, serving 21 subscribers. Within months, exchanges appeared in cities across America and Europe. The switchboard—a panel of jacks and cords that allowed operators to create temporary connections—became the technological heart of telephone service. The exchange transformed the telephone from a curiosity that connected fixed points to a network that connected any subscriber to any other.

The human operators were essential. They answered calls, asked for numbers, made connections, and announced when callers were connected. Initially, young men were hired, but their rudeness and tendency to prank calls led companies to replace them with young women—the 'Hello Girls' who became the voice of the telephone system. By 1900, tens of thousands of women worked as telephone operators, one of the first large-scale office jobs for women outside teaching and nursing.

The exchange created powerful network effects. Each new subscriber made the telephone more valuable to existing subscribers—they could now reach one more person. But this value was mediated by the exchange: subscribers of different telephone companies could not reach each other unless the companies agreed to interconnect. The Bell System recognized this dynamic and pursued aggressive expansion, acquiring competitors and refusing interconnection to independents. The telephone exchange was not just a technical system but a control point for the emerging communications industry.

The scaling challenges were immense. As subscriber counts grew, the number of operators required grew even faster—each call required human attention for its entire duration. The New York Telephone Company employed 6,000 operators by 1910. During peak calling hours, exchanges became chaotic as operators struggled to handle the load. The solution would eventually be automatic switching—the Strowger switch of 1891 and its successors—but for decades, human operators remained the essential interface between telephones and the network.

The telephone exchange established patterns that would recur in every networked technology: the importance of switching and interconnection, the natural monopoly tendencies of networks, the labor required to maintain human-scale service, and the organizational power of whoever controls the network's central node. When computer networks emerged a century later, they faced the same architectural choices—and sometimes made the same mistakes.