If you use Linux, you may download my little Beep-Beep bluebox to generate the tones.

To phreak my CCITT #5 exchange, you must dial-up the following number:

(i.e. 04644-9737083 from Germany)

The call will be answered before signalling starts, so that the audio path is through-connected for sure. Note that you are charged for the call to this number all the time until you hang up. Now you are able to break (send clear-forward tones) any time. Send the clear-forward tone:

2600 Hz + 2400 Hz, 150 miliseconds long

The tone will cause the current call to be cleared. The release-guard tone can be heared as anser to this tone. You can hear the start of this tone as a short 'chirp', the tone is muted as soon as it is detected, but continues. If you send the clear-forward tone too long, the release-guard will kick you out of the line.

Now send a seizing signal:

2400 Hz, 70 miliseconds long

You will hear a 'chirp' again. Alternatively you may use a 2600 Hz tone with 500 miliseconds to clear the line. Now you can dial with multi-frequency tones:


Only calls inside germany are allowed. The prefix is the city code without 0 in the beginning. Alternatively you may dial some internal numbers:

KP1-0-310-ST   my local carrier identification announcement
KP1-9090-ST    the initial announcement
KP1-90995-ST   music-on-hold
KP1-9001-ST    a local telephone
KP1-Code 11-ST a local telephone
KP1-Code 12-ST a local telephone
KP1-9091-ST    answering machine

You may leave some feedback about this project on the answering machine. If you leave your nick name and your will to make your recording public, your feedback may be downloadable on this web site.