Music on Hold (MOH) is a service used in PBXs. With the Music on Hold service, music or announcements are played during the time when the telephone connection is switched to the desired call partner or extension.
Music-on-hold can also be played during toggling, when a communication partner switches back and forth between two call partners.
In some PBXs, it is possible to select from a certain number of internally stored music tracks; in others, it is possible to play additional music tracks. The recording of music-on-hold may be subject to the GEMA tax code.