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LTE Voice/HD Calling DTMF Tone Incompatibility

This post is more just an informational post for other people experiencing the same thing I am. I have reported this through the product feedback as a bug report.


I have replicated this issue with three different iPhone 6's and one iPhone 6 Plus. All four phones are on Verizon's network. I initially had iOS 8.1, and have replicated the issue with 8.2 and 8.3 as well.


The HD Calling/LTE Voice setting I am referencing here can be found under Settings ->Cellular->Enable LTE->Voice & Data.


When HD Calling/LTE Voice is enabled, DTMF Tones stop working for INCOMING calls. OUTGOING calls work fine through automated systems. When I receive calls to complete surveys for my bank or cable company, (or the gate for my apartment complex) my DTMF tones are not registering on the far side. When I press the key on my keypad, I can hear the tone, but the far side does not recognize that a key has been pressed and the system continues on as if I am not doing anything. This usually results in either me getting disconnected for not pressing anything or, in the case of my apartment complex, people sit outside the gate and can't get in because the gate doesn't recognize my keypress telling it to open.


Turning the HD Calling/LTE Voice setting off does not fix the issue. The only way to get full DTMF Tone functionality back is to completely reset the phone using the Erase All Content and Settings option and DO NOT restore from a backup. I have tried both iCloud backups and local iTunes backups but the issue persists in those backups. I have also tried to isolate apps as the cause of the issue but I have replicated it with no apps installed so I am confident this is simply a problem with the iPhone's software itself.


I hope this helps!

iPhone 6, iOS 8.3

Posted on Apr 19, 2015 7:19 AM

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LTE Voice/HD Calling DTMF Tone Incompatibility

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