Dial tone
Special dial tone
Ringing tone or Queue tone
Busy tone
Congestion tone
Number unobtainable tone
Call waiting tone
Intrusion tone
Conference tone
Verification tone
Warning tone, expensive route
Dialog 3213
Audible Signals
The following different tones and signals are sent from the
exchange to your telephone.
Tone characteristics
The tones shown in this section are the most used tones
worldwide. Many markets use a differing tone for one or more
situations..
every 4th second
every 15th second (to all parties)
Audible Signals
87