From Wikipedia, the free encyclopedia.
In telecommunication, the term camp-on busy signal has the following meanings:
1. A signal that informs a busy telephone user that another call originator is waiting for a connection.
2. A teleprinter exchange facility signal that automatically causes a calling station to retry the call-receiver number after a given interval when the call-receiver teleprinter is occupied or the circuits are busy. Synonym speed-up tone.
Source: from Federal Standard 1037C
