No DTMF with some users while other can send DTMF

[fgc92210]

Hi,
We have an install where all users are remote and all users are using the Webclient through Chrome
There are a couple of users who cannot send DTMF at all, while every body else can.

When I compare those users to all other users, they all have the same Webclient version, and same DTMF Handling (RFC2833)

Any hint on what could prevent a client to send DTMF?
Regardless if they use their keyboard or click on the digits on the web client with the mouse, nothing is going out.

thank you all

 

[Alphabetic]

The receiving end, especially if it's an old system and doesnt support RFC2833.

for example, if you try the same number with your "working" extension, does it then work?

 

[fgc92210]

The receiving end, especially if it's an old system and doesnt support RFC2833.

for example, if you try the same number with your "working" extension, does it then work?

Yes, tried that. other extensions can send DTMF to this one number, while this one extension can't

 

[Alphabetic]

Can this extension DTMF at all? Can they log in to their VM using their PIN?

 

[fgc92210]

I did not try the voicemail. will check it out and update this thread.

 

[aschildmeyerSTR]

Yes, tried that. other extensions can send DTMF to this one number, while this one extension can't

For me I was having the issue with the windows softphone and then tried the edge extension and it worked fine. I was calling the comcast 1800 number. I then tried the windows softphone and it still wasn't working. I validated that RFC2833 is set on the windows softphone.

I use telnyx and have my codecs set as G722 then G711. I found this from Telnyx on there codec info page -

Note on DTMF:
The tones for DTMF are not transported reliably in G.729 and cannot be expected to work under any conditions. They're also not expected to work reliably with G.722, but may do so. DTMF should always work perfectly in any G.711 stream. DTMF tone frequencies were chosen to work with the PSTN, so must work reliably when encoded with G.711, which is the only codec in which we should expect no problems.

So I set the softphone to be G711 and retried calling comcast and it worked great, with not as nice sound quality but it worked. So I set it back to G722 and it's been working fine in the windows softphone since on G722. Super weird...

 

[fgc92210]

For me I was having the issue with the windows softphone and then tried the edge extension and it worked fine. I was calling the comcast 1800 number. I then tried the windows softphone and it still wasn't working. I validated that RFC2833 is set on the windows softphone.

I use telnyx and have my codecs set as G722 then G711. I found this from Telnyx on there codec info page -

Note on DTMF:
The tones for DTMF are not transported reliably in G.729 and cannot be expected to work under any conditions. They're also not expected to work reliably with G.722, but may do so. DTMF should always work perfectly in any G.711 stream. DTMF tone frequencies were chosen to work with the PSTN, so must work reliably when encoded with G.711, which is the only codec in which we should expect no problems.

So I set the softphone to be G711 and retried calling comcast and it worked great, with not as nice sound quality but it worked. So I set it back to G722 and it's been working fine in the windows softphone since on G722. Super weird...

Where did you see that G729 is no good for DTMF?
When DTMF are sent as a RTP-EVENT, it's in the signaling, and it's up to the remote party to treat them.
I ran traces in both G711 and G729, and the signaling shows exactly the same thing.
I have other systems which have been using G729 for the longest time, with never ever a single ticket raised about DTMF not working correctly.

 

[aschildmeyerSTR]

Where did you see that G729 is no good for DTMF?
When DTMF are sent as a RTP-EVENT, it's in the signaling, and it's up to the remote party to treat them.
I ran traces in both G711 and G729, and the signaling shows exactly the same thing.
I have other systems which have been using G729 for the longest time, with never ever a single ticket raised about DTMF not working correctly.

Historically I've been fine with G722 as well with DTMF.

Since I use Telnyx for trunking this is what I found from them.

https://support.telnyx.com/en/articles/3192298-audio-and-codecs in the DTMF section mentions it.

Though I wonder if they are referencing it for inband DTMF. Though you'd think G722 would be perfectly capable for inband DTMF when comparing it to G711. None the less flipping the codec on the softphone and having it go over G711 worked for RFC DTMF. ¯\_(ツ)_/¯

 

[fgc92210]

Very interesting, thank you for sharing. Not sure about the "can't be expected to work under any condition". I have the setup between 3CX and carriers in G711 , and the tcpdump traces I got show that the protocol used was 711. Still some issues arise. I spoke with the carriers (we tried 2), and we were able to reproduce the issue on both trunk. Flowroute said they did not see anything wrong, and will contact the carrier on their other side. We'll see how it goes. Interesting topic, and interesting debugging sessions