A homemade telephone lets you enter digits using a Morse key, displays the number on an LCD, and places a call when you press the MAIN button. For example, to call extension 31, you key in the Morse codes for 3 and 1. A push-to-talk speaker microphone gives conversations a radio-like feel.

Maker 7m4mon reused the enclosure, LCD and buttons from a test instrument built in 2008. An Arduino handles the input, while a Raspberry Pi provides the phone connection.