WHO INVENTED THE telephone? It is a famous question in the history of invention, partly because the standard answer—Alexander Graham Bell—is so widely known, and partly because Bell's claim to be the first inventor was shadowed from the start by a host of rival candidates. Versions of Bell's story appear in innumerable biographies and textbooks, scholarly works and movies. But for all the ink that has been spilled on the invention of the telephone, an under-appreciated fact remains: the very question “who invented the telephone?” is above all a legal artifact. What does it mean to invent a new technology? Who should receive credit, and with what result? Why do we care so much about identifying a first inventor? In the United States, these are questions that have persistently been asked and answered by the legal process, and nowhere more dramatically than in the case of Bell's telephone patent.

Alexander Graham Bell began experimenting with electrical sound transmission in Boston in the early 1870s. He did not initially aim to transmit speech. Instead, he joined a race to develop the “acoustic telegraph,” a type of high-capacity telegraph system that would carry multiple signals simultaneously on a single wire using sounds of different pitch. Many well known inventors of the day were chasing the same objective, including Thomas Edison and the electrical engineer Elisha Gray. But it was Bell—a teacher of the deaf who came to electrical invention from the study of sound, rather than the other way around—who had the crucial insight. Bell recognized that complex sounds could be transmitted using a continuous and fluctuating (“undulatory”) current, rather than the intermittent make-and-break current of the telegraph. By 1875, Bell's experiments with his assistant Thomas Watson were reproducing sounds with ever greater sensitivity: first the sound of a plucked reed. then inarticulate vocal noises.

With the help of his business partners and the elite patent lawyers they hired, Bell filed a patent application on 14 February 1876. The patent described a system of acoustic telegraphy based on Bell's undulatory current.