Caller ID was first invented by Greek engineer Theodore George “Ted” Paraskevakos , who developed and patented the original system for automatically identifying a caller’s number in the late 1960s and early 1970s.

Quick Scoop: Who Invented Caller ID?

  • The core idea of Caller ID — automatically sending the caller’s number to the receiver — was created by Theodore George Paraskevakos around 1968 while he was working as a communications engineer.
  • He filed an early U.S. patent in 1971 for a “decoding and display apparatus” that could decode pulses representing the caller’s phone number and show them to the called party.
  • From 1969 to 1975, he received around 20 patents related to automatic telephone line identification, which later served as “prior art” for other Caller ID–related patents worldwide.

So, if you’re asking who invented Caller ID in the foundational sense, the credit goes to Theodore George “Ted” Paraskevakos.

But Why Do Some People Say Kazuo Hashimoto?

The story didn’t end with one inventor, and that’s why you’ll sometimes see other names mentioned.

  • Japanese inventor Kazuo Hashimoto built one of the first practical caller ID display devices in 1976, turning the concept into something you could actually put on a desk and use.
  • He patented Caller ID in Japan in 1976 and later received a U.S. patent in 1980 for his system, which focused on the device that receives and displays the information.
  • His prototypes and devices were influential enough that some popular write‑ups casually label him as the inventor of Caller ID, especially when they focus on hardware rather than the original signaling method.

In short:

  • Paraskevakos : invented the underlying Caller ID method and signaling concept.
  • Hashimoto : invented a widely recognized Caller ID display device and secured key device patents later on.

How Caller ID Reached Ordinary People

Once the tech existed, phone companies had to decide how to offer it.

  • The first Caller ID prototypes were tested with telephone companies in the early 1970s, where Paraskevakos’s transmitter and receiver were demonstrated successfully in Alabama.
  • In the United States, one of the first public market trials of Caller ID as a service took place on July 7, 1984, in Orlando, Florida, under BellSouth’s “TouchStar” services.
  • Initially, phone companies debated whether Caller ID should be a voice announcement from the central office (e.g., a recorded voice saying the number) or a visual display on the phone ; engineers like John Harris pushed for the now‑familiar display model.

Mini Timeline

  • 1968 – Paraskevakos starts developing a system to automatically identify a caller.
  • 1969–1975 – He receives multiple patents that form the base of modern Caller ID tech.
  • 1971 – Prototype transmitter and receiver installed and tested in Alabama.
  • 1976 – Hashimoto builds a caller ID display prototype and files key device patents.
  • 1980s – Regional Bell companies begin marketing Caller ID services; a notable trial launches in 1984 in Florida.

Simple HTML Table of Key Figures

Person Role in Caller ID Key Dates
Theodore George “Ted” Paraskevakos Originated the method of sending caller’s number over the line; early patents for automatic line identification. Concept and development from 1968; major patents 1969–1975; key patent filing in 1971.
Kazuo Hashimoto Developed and patented practical caller ID display devices; major device patents in Japan and the U.S. First display prototype and patent filings in 1976; U.S. patent around 1980.
Information gathered from public forums or data available on the internet and portrayed here.