How does a landline phone identify numbers? Setting up Caller ID at home

This Habr article explores the Caller ID technology that replaced the traditional Soviet-era AON system. The author explains the principles of transmitting caller information over analog telephone lines, including the use of FSK and DTMF signals. The material details how the telephone exchange transmits data between the first and second rings. A significant portion of the article is dedicated to a practical guide: the author invites readers to build their own Caller ID decoding device at home. By using accessible components like microcontrollers and specialized chips, users can upgrade a standard landline phone into a modern device capable of displaying incoming numbers. This article is a valuable resource for electronics enthusiasts and those interested in the history and operational principles of classic communication systems.