A fast busy signal, technically known as a reorder tone, pulses at 120 interruptions per minute, twice the speed of a standard busy signal. It indicates that the call cannot be completed due to network congestion, an invalid number, or a routing failure, rather than the destination phone being off the hook.
Heard on the job
I tried dialing the overseas office but just got a fast busy signal, so the trunk must be down.
Also heard as
- reorder tone
- congestion tone
Do not mix it up with
- Busy signal: A standard busy signal means the person you are calling is on the phone; a fast busy signal means the network itself failed to route the call.
Related terms
Busy signal
A repeating audio tone that informs a caller the dialed line or network path is in use.
Engaged tone
An audible network signal indicating that the dialed number or circuit is in use.
PSTN
The global infrastructure of circuit-switched telephone networks operated by national and regional carriers.