Sine Wave Soundboard
Emergency Alerting
EAS Attention A two-tone alert played by the US's Emergency Alert System
NOAA 1050Hz NOAA Weather Radio's alert tone
Telecom
Dial Tone Indicates that a line is ready to make a call
Recall Dial Three quick on/off bursts, then continuous dial tone
Busy Signal Indicates that a line is busy
Ringback The 'ringing' sound heard when a call is connecting
Reorder Known as 'fast busy'; indicates that a call can't be completed
Special Information Tone Series of tones played before an automated message
Special Information Tone (Historical) Some systems used slightly different frequencies/spacing
Off-hook Tone indicating that a phone has been left off-hook
Call waiting tone The beep indicating another call is waiting while you're on a call
No Such Number 200-400Hz sweep that rises and falls continuously
Miscellaneous
1000 Hz Commonly used for calibration & testing