Hi All, anyone know about these DTFM tones used for access control, etc. I have been told that phone carriers are phasing these out, we are having problems when using iPhones for our gate access, we use the #9 for control.
Geo🇺🇸

 

I thought they phased out the tones for controlling a phone call long ago when people figured out they could use a tone generator to place calls and not pay. I think they are still used in some form to transmit information by telephone and cable companies to control remote equipment but I suppose that too is dying or dead because of digital.

Are you calling your gate on the phone and depressing number nine to access or are you pressing nine on your phone to produce the tone? If it's the tone you need I'm sure you can find an app that can produce whatever frequency tone you need.

 

When someone we know wants gate access they enter a 3 digit code on the key pad which inturn dials my iPhone # then I press 9 on my phone and that will or should open the gate.
Geo🇺🇸

 

That sounds a bit convoluted. You shouldn't need to be a middleman.

 

This whole place is convoluted, just trying to understand what these DTFM are all about, and if someone is blowing smoke, there is some good info online.
Geo🇺🇸

 

DTMF stands for dual tone multi frequency. When you push the button on a phone dial.... it's actually two frequencies at the same time. It uses a matrix of two frequencies for each button. One in a "high" group and the other in a "low" group.


One problem is that certain applications require several seconds of the signal while some cell phones will only transmit very brief bursts.

Keypad with actual tones

 

DTMF was the neato cool new technology that replaced rotary phones. As Pete mentioned, when you press 1 on your keypad, a certain frequency (pair of frequencies) is generated. Press 2, the frequencies are a bit different.
If you remember before cell phones, those land line things would make noises with every button you press to dial. That's DTMF.

A million things still use DTMF and I don't see it going away anytime soon. Not only do landlines still use it (yes, there are still landlines), but voicemail, auto attendants (press 1 for service, press 2 for sales), etc. are out there and will be for a while to come.

I did find some threads back from 2008 where people were complaining that their iPhones wouldn't connect to a company voicemail system since the tones were either too long or too short. Not sure if Apple fixed it, or the voicemail services were fixed. Haven't seen many threads/complaints since then Googling.

 

As for Geo's problem I don't even think a tone generating app on the phone will help since I don't know a way to make one app play a tone through the phone app. You might be able to use a handheld tone generator and hold it up to your phone but that would probably become a pita pretty quickly. It might be time to start looking for new controls for the gate.

 

Hi Guys, I understand the tone issue now, it maybe an IPhone issue, have to check around and see if it’s happening with other mfg’s.
Geo🇺🇸

 

Hi All, the problem occurs with different cell phones and different carriers, it would seem to point the carrier for the phone service at the office where all the security equipment is, any thoughts?
Geo 🇺🇸

 

I have similar problems with some remote control equipment here at my museum, and after pretty many tests together with the Telco: Callcentric, they managed to solve it. I'm not sure what they did, but they worked seriously and well to solve this, and solved it.