Audio Signals
Ringing signal
Internal busy tone
Internal dialling tone
External dialling tone/continuous tone
Positive acknowledgement tone
Negative acknowledgement tone
Special internal dialling tone
Special external dialling tone
Call-waiting signal
Special sensor signal
Ringer signals (analogue terminals)
External ringer signal*
Internal ringer signal
Time axis in seconds
0
1
2
3
4
5
6
* The first ring is a single ring, and all subsequent rings are periodic double rings.
The tones and ringer signals mentioned above are valid for Germany; in other countries they may differ.