The telephone was one of the first devices to be developed in our modern telecommunications system. In this laboratory project, working telephones are dismantled and reassembled. The telephones must continue to work properly after being assembled. In the second part of the project, broken telephones into which known problems have been introduced will be repaired. The project shows applications of electromagnetism in the telephone microphone and speaker, and develops skills in diagnosing and repairing problems with technological devices.