Conky 2000 wrote:AllSafe wrote:DTMF (dual-tone multi-frequency) tones transmitted with the voice signal. They are used to control the siren. It is usually a sequence of numbers with * and # to mark the beginning and end of the tone sequence.
So it would go like, for example, "*1234#", because there are six tones? Also, is there a number that they call on a phone to activate the DTMF, or must it be done from a pager or electronic control panel?[/quote
DTMF is just a sound, a noise. It can be transmitted through phone wires, radio waves, laser beams, or a squawking bird (if it could sound the same dual notes). DTMF is not limited to phones. You cant dial a siren up from a phone if its not hooked to the phone system. They just use DTMF as a substitute for the two-tone paging because more commands can be given more quickly. Remember, DTMF is just a sound, nothing more! There are many devices and technologies that can manipulate sound and use it to activate and control devices.