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From the Black Rotary Phone to the Smartphone - 130 Years of Telephone Evolution

About 14 min read

The Birth of Telephony in Japan - 1890

Telephone service in Japan began on December 16, 1890 (Meiji 23), when telephone exchange operations started between Tokyo and Yokohama. The initial subscriber count was a mere 197. The phones were wall-mounted wooden units with separate earpieces and mouthpieces. To make a call, you turned a crank on the side of the phone to summon an operator, then verbally requested the connection: "Number XX, please." At launch, there were 155 subscribers in Tokyo and 42 in Yokohama, and service hours were limited to 7 AM to 9 PM.

The annual telephone fee was 40 yen - equivalent to a police officer's annual salary at the time. The telephone was a luxury affordable only to the wealthy and businesses. Subscriber numbers were short, ranging from 1 to 4 digits. Tokyo's number 1 was assigned to the Tokyo Prefectural Office, and Yokohama's number 1 to Yokohama City Hall.

The Magneto Phone Era - 1900s to 1950s

Early telephones were "magneto" types: turning a crank generated electricity that lit a lamp on the switchboard, summoning the operator. Call quality was incomparably poor by modern standards, requiring callers to shout over heavy static.

In the 1920s, automatic exchanges began to be introduced. Tokyo's first automatic exchange went live in 1926, allowing callers to connect by dialing a number themselves. However, the rollout was gradual from urban to rural areas, and some regions relied on manual operator connections into the 1970s.

The Golden Age of the Black Rotary Phone - 1950s to 1980s

The most iconic telephone in Japanese history is the "black phone" (kuro-denwa). Officially the Model 600 (later improved to Model 601), it debuted in 1962 with its distinctive black Bakelite body and rotary dial. NTT's predecessor, the Nippon Telegraph and Telephone Public Corporation, manufactured and managed these phones centrally, renting them to subscribers.

The black phone's proliferation was driven by Japan's rapid economic growth in the 1960s. Telephone subscriptions surged from about 3 million in 1953 to about 30 million by 1975. "One phone per household" became the norm, transforming the telephone from a luxury into a necessity. The "ji-ko, ji-ko" sound of the rotary dial became an iconic soundscape of Showa-era homes. Retro black rotary phones are also popular as interior decor.

A key technical feature of the black phone was that it ran entirely on power supplied through the phone line. No external power was needed, so it worked even during power outages. This characteristic remains critically important for disaster communication and is an advantage that modern IP phones lack. It is also a point to consider when evaluating whether to cancel your landline.

The Arrival of the Push-Button Phone - 1969

In 1969, the push-button phone (officially the Model 600P) arrived as a replacement for the rotary dial. Instead of turning a dial, you simply pressed buttons, dramatically reducing dialing time. Dialing "0" on a rotary phone took about 1 second; on a push-button phone, it took less than 0.1 seconds. Dialing a 10-digit number dropped from about 10 seconds to about 2 seconds.

Another innovation was the adoption of DTMF (Dual-Tone Multi-Frequency) signaling. Each button was assigned a unique combination of two frequencies, and this audio signal conveyed the number. Since DTMF signals could be sent during a call, they became the foundation for IVR (Interactive Voice Response) systems. The familiar "Press 1 for..." voice guidance was made possible by push-button DTMF technology.

The Cordless Phone Revolution - 1980s

Cordless phones, introduced in the 1980s, fundamentally changed how people used telephones. Until then, a phone was "something fixed to the hallway wall," and you had to stand in front of it for the entire call. Cordless phones let you carry a handset around the house, transforming the telephone into a communication tool free from a fixed location.

Early cordless phones had poor call quality and eavesdropping risks, but digital technology improved both quality and security. In the 1990s, features like answering machines, Caller ID Display support, and FAX integration drove further evolution. The cordless phone also changed where phones were placed in the home - from wall-mounted units in the hallway to tabletop units in the living room or bedroom. The phone shifted from "shared household equipment" to "something you keep within arm's reach." This shift arguably prepared people psychologically for the later adoption of mobile phones.

The Mobile Phone Era - 1990s Onward

NTT launched mobile phone service in 1987, but the initial handset was a "shoulder phone" weighing about 3 kg with a monthly fee of 26,000 yen. Through the 1990s, handsets shrank rapidly and prices fell. In 1999, NTT DoCoMo's "i-mode" brought internet connectivity to mobile phones.

The 2007 iPhone launch triggered the rapid spread of smartphones, transforming the phone from "a device for making calls" into "a terminal for accessing all information." Ironically, one of the least-used features on a modern smartphone is the phone function itself. According to the Ministry of Internal Affairs and Communications, the average daily call time for smartphone users is about 3 minutes, with messaging apps and social media dominating communication.

Our VoIP basics guide and Hikari Denwa migration guide are also useful for understanding where telephone technology stands today.

The Future of the Telephone

Looking back over 130 years, the evolution of the telephone is also a history of "liberation from place." From the magneto phone fixed to a wall, to the cordless phone that freed you within your home, to the smartphone that lets you call from anywhere in the world. The next evolution may be "liberation from the hand" through wearable devices and AR glasses. The essence of a phone call may not change, but the means will continue to evolve.

Moments When the Telephone Changed Society

Telephone innovation did more than improve devices - it reshaped society itself. Automatic exchanges eliminated the operator profession. Cordless phones ended the habit of "standing in the hallway to talk on the phone." Mobile phones fundamentally changed the concept of "meeting up." Before mobile phones, people arranged meetings with precise times and locations: "3 PM in front of the station." After mobile phones, "call me when you get there" became the norm. Understanding how phone numbers work is also a key to reading the social changes behind these technological shifts.

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Frequently Asked Questions

When did telephone service begin in Japan?

Telephone exchange service began on December 16, 1890 (Meiji 23), between Tokyo and Yokohama. There were only 197 initial subscribers, and the annual fee was 40 yen - equivalent to a police officer's yearly salary at the time.

Why does the black rotary phone work during power outages?

The black rotary phone operates solely on power supplied through the phone line (exchange power). It requires no external power source. As long as the telephone exchange's batteries are running, calls can be made even during a blackout.

What do the tones on a push-button phone mean?

Each button is assigned a unique combination of two frequencies called DTMF (Dual-Tone Multi-Frequency). These audio signals convey the dialed number and also form the foundation for IVR (Interactive Voice Response) systems used in automated phone menus.

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