"Cancelling" DTMF

[samo]

I should probably start this thread off by defining what I mean by canceling. By canceling, I mean to produce a noise that, when played into the microphone, would make DTMF tones that were being played unrecognizable to whatever system they were being played to.

So, is canceling DTMF tones possible? I've read from a few text files that you can "hiss" into the microphone of a COCOT when the COCOT is sending DTMF digits to the switch after giving you a false dialtone and cause the switch to not decode these digits at all, therefore giving you an unrestricted dialtone.

This wouldn't apply just to COCOTS though (most of them mute their microphones anyway), there are probably a few other things this would be useful for. Thanks.

[legend813]

Blowing into a cocots mouthpeice only prevented the cocot from 'hearing' the CO produced dialtone what was sometimes returned by
certain types of switches that gave you another dialtone after the party you had just dialed, hung up. That was an early security feature, the phone only wanted you to hear and use its own, and it was programed to shut itself down if it heard another dialtone.

[johnnyhacker]

Blowing into a cocots mouthpeice only prevented the cocot from 'hearing' the CO produced dialtone what was sometimes returned by
certain types of switches that gave you another dialtone after the party you had just dialed, hung up. That was an early security feature, the phone only wanted you to hear and use its own, and it was programed to shut itself down if it heard another dialtone.

Why yes Legend you are correct! Now on the new Digital Singaling System/CCS7 switches an alarm tag pops up on the console, notifying the STC that dialtone has become erroronious. I have attached a handy manual that might help you out with thing telephonic.