busy tone —A low-pitched tone repeated 60 times a minute; indicates the number dialed is in use.
call waiting tone —One, two, or three beeps of high-pitched tone, not repeated; indicates an incoming call is waiting to be answered. Number of beeps designates the source: one for an internal call, two for an outside or attendant call, three for a priority call.
call waiting ringback tone —A ringback tone with a lower-pitched signal at the end; indicates the extension called is busy, and the called party has been given a call waiting tone.
confirmation tone —Three short bursts of tone; indicates a feature activation or cancellation has been accepted. When you have finished selecting a ringing pattern for your voice terminal, you hear two rising tones.
coverage tone —One short burst of tone; indicates your call will be sent to another extension to be answered by a covering user.
dial tone —A continuous tone; indicates dialing can begin.
intercept/time-out tone —An alternating high and low tone; indicates a dialing error, a denial of the service requested, or a failure to dial within a preset interval (usually 10 seconds) after lifting the handset or dialing the previous digit.
local error tone —A steady low tone; indicates an incorrect button press.
recall dial tone —Three short bursts of tone followed by a steady dial tone; indicates the feature request has been accepted and dialing can begin.
reorder tone —A fast busy tone repeated 120 times a minute; indicates all trunks are busy.
ringback tone —A low-pitched tone repeated 15 times a minute; indicates the number dialed is being rung.
speakerphone reset tones —A rising set of tones; indicates the speakerphone is adjusting itself to the surrounding room acoustics.
