Call Queues and Ring Groups destorying DTMF tones

[ezcleancarwashes]

I've searched around and haven't seen this exact example pointed out. I will be as thorough as possible. The call flow cases are as follows:

CASE 1 (Working):
Inbound automated call from a SIP endpoint via SIP trunk to an extension that is unregistered, or out of office > forward to outside PTSN number > call answered by extension owner > extension owner triggers a DTMF tone and the Inbound calling device CAN recognize the DTMF tone and work appropriately.

CASE 2 (Not working):
Inbound automated call from a SIP endpoint via SIP trunk to a RING GROUP > forward to one or more internal extensions > forward to outside PTSN numbers > call answered by extension owner > extension owner triggers a DTMF tone and the Inbound calling device CAN NOT recognize the DTMF tone and work appropriately.

This exact same behavior is present with call queues. Something about using call queues, or ring groups is destroying DTMF tones. I've trying changing and restricting codecs, pbx audio, almost every option that there is, and it works fine if you use a regular extension rather than a ring group. I'm running 3CX on google compute, with Callcentric trunking.

Can anyone help me troubleshoot where my DTMF tones are going when utilizing ring groups or call queues?

Thank you,
Danny Henderson

 

[leejor]

It may be a Codec Issue. Low bit-rate Codecs cannot handle audio DTMF properly, if that is being used along the way. Perhaps check the Activity log to see if transcoding is happening, or what Codes are boing used. Generally G.711 A/U works best.

 

[ezcleancarwashes]

Thank you for your reply! I have tried setting my SIP trunk to use G.711 A/U with no difference. If an extension is dialed directly and then forwarded back to PTSN, everything works. 3CX is only eating DTMF tones when using call queues and ring groups. I believe this may be due to the fact that these are "internal" calls which the codec seems to be set for under general options. Changing the order of these codes also presents no change. Audio quality is clear and bandwidth is not an issue as this is Google Cloud.

 

[JohnS_3CX]

Perhaps if you run a capture on your PBX for both scenarios, using the same ext. and PSTN number and compare between them?

You can see what codecs where actually used in one VS the other, you will see any DTMF signals (unless they are in-band and only go as audio)

 

[ezcleancarwashes]

Thank you so much for your suggestions, I have gone through many captures in Wireshark and also the verbose logs. After your suggestion, I have tried to eliminate more variables and I can simplify the situation a bit more.

SIP trunk: Callcentric
Advised UA settings per Callcentric's website:
1 - G.711 u-law
2 - G.711 A-law
3 - G.729

I'm using EXT 0000 for dialing, a SIP endpoint registered at my 3cx cloud installation.

EXT 0000 outbound call directly to a PSTN (cell phone), the SIP dialer can receive DTMF tones from the cell phone.

EXT 0000 internal dialing 8000 (a Call Group) which connects only to the exact same cell phone, the call connects and the SIP endpoint does not recognize DTMF tones pressed by the cell phone.

This nearly rules out a SIP trunking problem or a codec mismatch. The problem is internal to 3CX treating something differently about the call path being routed through a call group rather than directly outbound.

I can easily post any logs or captures that may help.

Thank you!

 

[JohnS_3CX]

Are you using the Ring My Mobile simultaneously feature in your flow by any chance?

 

[ezcleancarwashes]

Thank you so much for your reply, I was indeed. Disabling this feature does allow for the DTMF tones to work when dialing extension to extension!

The setback is now any phone that is unregistered, does not ring through to the affected extension, regardless of the forwarding rules. With the "ring my mobile" enabled it forces the extension to stay registered.

It appears that ring groups ignore "If I am busy or my phone is unregistered, forward calls to: ".

Perhaps that needs it's own thread, and again, I really appreciate the help.

 

[ezcleancarwashes]

For anyone following along or reading this, JohnS_3cx was 100% right that using ring mobile simultaneously was the cause of the lost DTMF tones in this instance. I am not sure how or why that is, but that was certainly the case for me.

Now I'm stuck at this problem here, which wasn't a problem before I disabled that feature:

https://www.3cx.com/community/threads/problem-with-ring-groups.4931/

The ring groups do not seem to follow logical call flow with the extensions forwarding options. If you have two extensions in a ring group that are both unregistered and set to forward to a a number if unregistered, the ring group follows it's own "no answer" flow with priority.

I tried their solution of:

ALLOWUSEBUSYOPTFORGROUP

="1" will enable use of phone 'Busy' status instead of 'PBX status' for members of ring groups

1

After restarting all services, the ring group still ignores all forwarding options. I will try more settings and leave an update. Any ideas are welcome.

 

[ezcleancarwashes]

It appears I'm not the only one in this use case that needs calls to ring through even when unregistered from the app:

https://www.3cx.com/community/threads/push-extensions-not-registered.62589/

Is there any workaround seeing as "Ring Mobile Simultaneously" eats DTMF tones so that isn't an option for me.

 

[leejor]

Did you look at the detailed (Verbose) Activity Log when the ring my mobile is enabled, to see if there is some reason (low bit-rate Codec used on outgoing trunk?), why DTMF isn't working? Perhaps compare, side by side, with a call when the feature has been disabled.

 

[JohnS_3CX]

Hi @leejor and @ezcleancarwashes

The Mobile Transfer Agent Service allows you to perform certain operations with dial codes when you use the Ring My Mobile Simultaneously option, hence the PBX "captures" the DTMF for this feature to work and diverts the commands to the PBX so you can have hold/transfer/conference via a GSM call.

https://www.3cx.com/docs/pbx-dial-codes/#h.mlp4gmj167pe

 

[ezcleancarwashes]

John, thanks for the additional information. Is there a way to turn off this functionality so the DTMF tones will work when using this feature? Or as you see above is there a way to use unregistered extensions with call groups? Either of these solutions would work for me, but as you see I ran into above, call groups don't follow the forwarding rules of unregistered extensions. And if I use the ring simultaneously to get around that problem, then I lose DTMF tones.

 

[JohnS_3CX]

For the Ring Groups behavior, this is indeed correct. They are designed to run as a separate extension, which will poll the agents that belong to the group, and if the agents don't respond it will take you to the destination if no answer. It is not designed to use the forwarding rules of each agent. You cannot disable the DTMF functionality nor keep the extension permanently registered if it is not attached to a registered device.

Depending on what your end goal is, the functionality you are trying to achieve could possibly be done using other methods like the 3CX Call Flow Designer.

 

[ezcleancarwashes]

I've taken a look at the CFD and I think this is actually a solution that will work. I can't find exact information on 3CX cloud using your Call Flow Designer.

https://www.3cx.com/community/threa...ow-designer-and-where-to-upload-on-v16.64265/

Is it no longer supported for v16 cloud deployments?

 

[JohnS_3CX]

Hi Danny,

It's supported in V15.5SP6

For V16 please take a look at Update 1 Preview Build here https://www.3cx.com/blog/releases/call-flow-designer-v16/