DTMF tone not present while call in progress

[jakthree]

3CX v15.5.15502.6 standard annual
Windows Client 15.5.12227.5

The extension only has 3CX web client and 3CX windows client. The web client is not open. All dialing is done thru the windows client.

Problem:
3CX user dials company A using windows client.
Company A answers and an IVR says 'Press 1 for support, Press 2 for sales, Press 3 for ...'
Clicking 1 on client keypad does not send DTMF to company A.
Clicking any number on the client keypad generates the same tone as heard in the 3CX users headset.

The client does not generate the DTMF tone for the number 1 (or any number clicked).

The problem also happen using the iOS client and the android client.

If the users repeats above but dials through the web client then the DTMF tone is sent.

Is there a setting in the client(s) that prevent sending of the DTMF tones while the call is in progress?

Thank you,

 

[YiannisH_3CX]

Hello @jakthree

The DTMF method for the windows client can be set under the extension settings for the 3CX client. You can also see it under settings / Configure Accounts / Eidit your account / Advanced Settings / DTMF Method. The default should be RFC2833.
May i ask how did you verify that a DTMF tone is not sent from the windows client? What happens if you call a local IVR? Can you send DTMF tones there?

 

[eddv123]

Your 2 DTMF methods are RFC 2833 (out of bandwidth method) and SIP INFO (Inband method).

What this means is DTMF is sent in either in the media path or in the SIP flow.

If using SIP INFO beware of using compressed codecs and if traversing media gateways ensure that you have DTMF relay enabled.

You can also run a Wireshark trace to see if the DTMF packets are being sent, it is very easy to see these.

 

[jakthree]

More background.
I am not using a SIP provider. I have Grandstream GXW4108 FXO gateways. The GXW DTMF Method is set to RFC2833 only. I have studied this link https://www.3cx.com/blog/voip-howto/dtmf-rfc2833/. It makes sense that a desk phone has a tone generator in it and when a key is pressed the DTMF tone is inserted over the voice audio and heard on both ends. However I am confused as to how the DTMF tone is generated when using the web, windows, android or iOS clients.
Do the clients have a tone generator built into them?

I may not understand the process of transporting the DTMF tone and/or voice over PSTN correctly.
The tone generated by a client, is converted by a codec, into a SIP packet and transported inside SIP packets to the GXW gateway. The gateway then converts the SIP packets into an analog audio/voice PSTN signal and simply passes the tone. The SIP packets do not pass through the gateway. What I don't understand is...
Is the DTMF tone's analog signal converted via codec (analog to digital) or is the DTMF tone converted to a some type of 'control code' and placed into the packet?
Does the GXW have a DTMF tone generator built into it that is triggered by the 'control code'?

May i ask how did you verify that a DTMF tone is not sent from the windows client? What happens if you call a local IVR? Can you send DTMF tones there?

YiannisH_3CX,
I cannot hear the DTMF tone in my earpiece and the number called does not react to the tone. I have not tried packet capture yet.
I don't have a local IVR setup.

Your 2 DTMF methods are RFC 2833 (out of bandwidth method) and SIP INFO (Inband method).

eddv123,
I set the GXW's DTMF method is set to RFC-2833 only, thinking that I don't need SIP INFO because I think 3CX does not send SIP INFO to the unit because it is a gateway and not a SIP provider. The GXW does have in-audio and SIP INFO methods available. It makes sense that a SIP provider might want SIP INFO, but why would the GXW need SIP INFO since SIP packets are not passed through the gateway? I am not questioning your reply. I guess I need a better understanding of what the gateway does when it converts the codec into analog.
I will do a pcap and use wireshark to look at a conversation between 3CX and the gateway.
What does a packet with a DTMF tone look like when converted by PCMU codec?

Thank you,