DTMF Tone on IOS 13 issue

FIX: switch to 4G by turning off LTE

I can say with a high level of confidence that if your having this issue it's not the iPhones fault. This is almost definitely an IVR setup/development issue.

I develop and integrate IVR systems and have had this issue personally. It's an issue with how the IVR is handling the touch tone, its not an issue with the iPhone. We had this issue on our IVR systems and resolved it, but since you can't control the IVR systems here's what you can do to get it working: turn off LTE and use 4G when calling into an IVR that doesn't recognize your DTMF's.

I was able to record the DTMF's that the IVR received from the iPhone (note: this does not mean the iPhone created this, it just means that by the time it got to our system it was represented as seen; there can be intermediary systems that affect this).

Results:

When using and iPhone on ATT LTE the touch tones look PERFECT. I mean perfect. They are to the spec, exactly. I've never seen any other touch tone come through so perfect. They were exactly the length required, were spaced out exactly as needed, etc etc. When switching to 4G the perfect touch tones degraded but looked like any other ones we get on the system. The touch tones on LTE did not work, 4G did.

In our case the touch tones were being sent to a speech recognizer that then sends back DTMFs if it detects them. Once we changed our setup to recognize OOB touch tones it worked (it didn't have to send them to the speech recognizer, the driver that we have recognized them correctly and we just changed the driver to send us the touch tones instead of relying on the speech recognizer). There are reasons for having the IVR setup this way and in some cases the fix won't be as simple as it was in ours.

I was able to resolve this issue on my iPhone 11 Pro Max running iOS 13.5.1 by disabling WiFi Calling. Settings>Cellular>Wifi Calling>Off. I don't think its enabled by default -- I know I turned it on a few months ago because I was in an area where I needed it, but if you do have it enabled, I'd try disabling it.

I was having the same issue with my iPhone 11 and AT&T. Spoke with both Apple support and AT&T. Carrier had me reset my network settings on my phone AND they also disconnected/reconnected my sim card from the network. This worked for me and now I can use the IVR systems. I will continue to see if this solution works through the weekend. It may be worth a call to AT&T to have them disconnect/reconnect your sim card to the network and reset your network settings on your phone. Hope this helps someone.

UPDATE: So I managed a workaround for my particular issue with my front door buzzer.

Settings > Cellular > Cellular Data options > Voice & Data

I ebelive the newest iOS set this option to "LTE,VoLTE On"

I set it to "LTE,VoLTE Off" and this seemed to have done the trick to allow me to press "6" to open the door

Hopefully this might help some of you!

I'm still not accpeting that this is a the actual fix....there is definitely something else buggy

I had this problem with my iphone8SE 2020. I had to turn off “Enable LTE” in settings. Cellular>Cellular Data Options>Enable LTE

It probably is ATT's fault, well sorta. I develop IVR systems and we had this issue, but only with ATT and ONLY using LTE. If I switched to 4G then it worked. I have an answer post in here as well explaining just a bit more. But the point is that Apple is going to send its touch tones to the cell tower (not as audio but as touch tones) and the towers/switches along the way might alter them or create new packets all together to represent the touch tones.

The touch tones I got from ATT on LTE were literally perfect. The issue was in the way the IVR handled touch tones. Either way it's not going to be on the iPhone to change ATT's DTMF generation/propagation.

I am having the same issues with my iPhone 11 Pro. I thought it was the phone and went searching on the internet for a solution only to discover the issue is with the iOS13. So far haven’t found anything to fix this problem, but if you are on speaker phone it works. I called my cell carrier today and had it on speaker phone to choose my options until I got to where I needed to be. Hope this helps until this issue is resolved.

LTE set to off worked on iPhone 6 Plus. After recent iOS upgrades, our answering system could not hear remote commands from the phone. LTE off solved the problem. Note: our old iPhone 5 (now on a pre-paid/pay for use plan) has no trouble waking up our answering machine. (Apple’s relentless drive for planned obsolescence sure makes it tough for those of us trying to make trailing-edge technology last as long as possible. )

Try turning off LTE

I had this problem when trying to verify 2FA from paypal. I found if you switch to speakerphone you get the tomes back.

as a retired telecom engineer for 35yrs i would like to suggest that Apple use a slightly longer DTMF tone as many IVR's look for a minimum of 50ms tone duration before "recognizing/validating" the tone. My personal experience after 10yrs as the CallCenterGuy, is 80-100 ms should be sufficient as it is neither too long or too short for most well designed systems. This is mostly due to ambient noise issues (background noises) or poor quality connections. Please consider an option to allow/tune for longer tones and do your homework/product testing BEFORE releasing any new IOS to the real users. THANKS!

Although it is not a final solution, I found that using speakerphone to enter the IVR numbers works on all of my devices and even on the android devices that my friends had this issue with.

In short, try on Speakerphone and leave feedback on Apple.com/feedback

I mailed a letter to Apple and explained the issue. I explained that a software update was much better than updating thousands of the "buzzer" doors and gates. In an update about a month ago, I noted that the DTMF tones "appeared" to be now working properly. Yesterday (01/18/21) Amazon rang my gate and front door and the DTMF tones WORKED! I am running an iPhone 11 with iOS 14.2 and T-Mobile as of today. For what it's worth, I also mailed T-Mobile as the Apple community seemed to think it was both the carrier and Apple's fault that the DTMF were not working.

I also mentioned in the letter that people say that a "properly designed" gate system should accept short tones. True, but according to my gate company (and others that I talked to) there are many more legacy systems out in the world than ones that will accept short tones. Also one must include the banks, credit card, insurance companies, etc. that have legacy systems. If it ain't broke, why buy a new one! Finally, the "mountain moved to the user", not the other way around!

Yes... we had to revert one of our iPhone 10’s back to the 8 so we can open the gate... all other versions of the iPhones work and so do the androids.