Following recent communication issues, NASA's Voyager 1 spacecraft resorted to a backup radio transmitter that has been inactive since 1981.

Voyager 1 spacecraft phones home with transmitter that hasn't been used since 1981

Source: space
Source Link: https://www.space.com/space-exploration/missions/voyager-1-spacecraft-phones-home-with-transmitter-that-hasnt-been-used-since-1981