Annoying beep sound during call transfers IVR

[V.Thierry]

I have created a new flow in 3CX.

But I came across "issue" that I can't seem to fix.
The Call Routing (CR) is a sequence of IVR and Call Queue's (CQ).
But when a call is forwarded from the IVR to a CQ, you will hear an annoying “Beep” tone and vice versa from CQ to IVR.

From IVR to IVR there is no issue.
I can't find much information about it online.

The setup* is;

1 for Dutch (IVR)
1 for Industrie (IVR)
1 for Property (IVR)
“Beep” then forwarded to CQ
After 20 sec (fallback)
“Beep” then forwarded to a new IVR

When pressing 1 (to leave a voicemail), another “Beep” (not the beep from the voicemail) after the voicemail text has been played, the voicemail beep happens correctly.

*this is only a part of the setup, ofc the IVR contain more option with similar configuration and all have this issue


Also, the beeps from the forwards differ from the ones from the voicemail.

I can't find this kind of sound in the system prompt, nor has it been uploaded.


It's very annoying.


Tested on iPhone, Android and landlines all the same, so it must be in the system.

Also, a newly created setup with no messages gave the same issues.



Version 18.0 update 3 (Build 461)