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.

 

I still have a home phone line, but the service is VoIP through the internet, converted to an analog line. Since it's VoIP and there's packets, losses and other situations involved the provider I use will regenerate a DTMF tone locally in the ATA (Analog Telephone Adapter) in the house. That provides a 'pure' set of DTMF tones to represent a digit. Sometimes during a conversation I'll hear a DTMF digit because the system perceived what was close to a DTMF digit when someone was speaking.

Is the phone service from the local phone co. - or another source like the cable TV company? The trouble you're experiencing isn't typical of local phone co, service, unless the line quality is bad. It sounds like the gate access system expects to receive a certain length of a DTMF digit - but it's too short. Maybe you can try it from an analog phone - press and hold the digit for one second. if it works hopefully the system can be adjusted to accept shorter duration tones.

Years ago there when MF (multi frequency - similar but different tones from DTMF) was used for long distance calls there was a particular tone set I believe that when generated would indicate the call terminated - but if both parties stayed off hook the conversation would continue. Some of us older members may recall hearing a sequence of tones a few seconds after dialing - or should I say pressing a long distance number. Those were the MF tones that contained the called number and other information.

As Zorfdt said - DTMF will be around for a while. Sure, when you access your cellphone's voicemail system that's all digital - no analog tones involved, but calling into your work voicemail or an auto attendant - that's DTMF which is the standard that all the systems were designed for.