The first telephone numbers were used in 1879 in Massachusetts to replace connection requests made by callers to a switchboard operator. Back then, phone numbers only had one to three digits. As it became a worldwide means of communication, numbers became longer.
Even after adopting phone numbers, “central” operators manually connecting most calls was still the norm in the first decade of the 20th century: “Hello, Central. Get me Carter-342.” It was during the 1920s when direct-dialing of numbers started to gain popularity.
An important milestone in the history of phone calls and reverse cell phone lookups was in 1879 when the first telephone directory was issued. It listed 50 telephone owners (businesses and individuals) from in New Haven, Connecticut, on a single piece of cardboard.
Later, telephone directories or phonebooks diversified, and had different colors, depending on the type of phone numbers they listed