Fritz-Box: No busy signal audible from the caller

Fritzbox busy signal when busy

Since I've had my [Fritz! Fon MT-F-> fritz-fon-mt-f] on my newly set up Fritz! Box, callers have always told me that they hear a normal ringtone when the line is actually busy . But I didn't hear a call myself. For further information: I use the [Fritz! Box 7390-> fritz-box-7390] with the [current 6-series firmware-> fritz-box-firmware-update] and have a VoIP connection from Telekom.

I didn't want the "call waiting" feature anyway, but I find it a bit confusing for callers when I'm already on the phone and they don't get a busy signal but a dial tone. That's why I switched it over to my Fritz!Box. This can be done via the configuration menu of the Fritz!Box. There you select the item “Telephony” -> “Telephony devices”. There you click on the corresponding device and then select “Characteristics of the telephony device”. The selection is then made in this menu

Reject call when busy (Busy on Busy).
Incoming calls are rejected if the called number has been set up on the telephony device and a call is already being conducted via the telephony device.

The setting is still saved and from this point on the caller should always receive a busy signal if the connection is already busy. So that you know what the menu looks like, I've included a screenshot here.

Fritzbox busy signal when busy
This is how you set the Fritz-Box so that a caller also receives a busy signal when the line is busy.

For those who have a speed port from Telekom, the setting is very similar. I got it from the “” site and just use it here without checking it because I don’t have a speed port:

Go to the configuration program of your speed port and there to the item “Telephony”. Choose whether it is landline telephony or Internet telephony. From there, click on “Settings”. The “Reject on busy” box must be ticked for the phone numbers so that a busy signal is generated.

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6 Responses to "Fritz-Box: No busy signal audible with caller"

  1. I thank you a thousand times for your contribution. I have had the Fritzfon with Fritzbox for a few days and actually think it's quite good, except for this thing. But thanks to you, the confusing calling has an end with the busy signal!

  2. But it doesn't work for me. I made exactly these settings. I also have 2 more DECTs. All devices are assigned to the same phone number. Does anyone have any advice?

  3. Sebastian Bertram

    This corresponds to the instructions from AVM to solve the problem - after changing the settings accordingly
    however, the following behavior occurs on the Fitz! Box:
    The second caller on the busy line first receives a dial tone five times and then an announcement that the number is temporarily unavailable.
    This is now even more unsatisfactory than the irritating dial tone before, because callers who hear this tell me that the line has been redirected to a mobile number that no longer exists! That is not at all what is being conveyed
    should! I just want a simple busy signal!
    Since the conversion of the original ISDN connection to VOIP, the drastically reduced functional reliability has also been frustrating: there are now several prerequisites for successful call switching, all of which must be met at the same time.
    In contrast to the ISDN line, not only this line must work, but there must also be power for the router and any Internet telephony-specific functions must be guaranteed!
    I keep finding out that Trlefonie is not possible because the phone numbers are currently not registered.
    My router then indicates that I am trying to reach me by flashing the telephone LED - but it does not ring and I cannot call anyone either.
    How should important things be organized under such conditions?
    Neither disaster control nor the requirements of industry or important institutions can be guaranteed with telephone networks from earlier colonial times!
    It's a step back more than 50 years!

    1. Hello Sebastian! These are of course not good conditions ... if you rely on the telephone as a means of communication, it shouldn't be. But unfortunately I don't have any advice on what you could do to fix the problem.

  4. Subject.
    “Fritz-Box: No busy signal audible when calling”

    Thank you very much,'
    I almost searched to death looking for "knock".
    And here - in a nutshell.

    Thank you very much!

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