Most bug detection devices focus on discovering listening devices, wireless and wired spy camera devices.
As an add on they are also able to perform bug detection on telephone lines, but this is not quite the full story, because there is more than one way to bug a telephone line or what is commonly known and 'telephone tapping'.
The most common perception is that lines are tapped by placing a bug (radio frequency transmitter) on the line that transmits what is being said to a receiver located a short distance away. However, telephone lines can be bugged in other ways. Most common is the attachment of a recording device onto the telephone line. These units will start recording when the phone is picked up and stop recording when the phone is put back down. Our telephone tap defeating devices are able to counteract these by constantly sending a high pitched noise down the telephone line even when the receiver is down. This noise will of course be recorded by any attached tape or digital recorder. The tape or digital memory will fill up and the telephone recorder will then be rendered as useless. This method with also defeat GSM based telephone bugs, so in order to maintain landline integrity, then telephone tap defeats are a very useful tool