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Knowledge document #124

FRITZ!Box 7583

This support document is available for the following products:

Callers do not hear busy signal when a call is already being conducted via FRITZ!Box

Callers hear a ringing tone instead of a busy signal if a telephone call is already being conducted over the FRITZ!Box. The caller therefore assumes that the line is free.

Simply proceed as described below. After each measure, check whether the problem is solved.

Note:All instructions on configuration and settings given in this guide refer to the latest FRITZ!OS for the FRITZ!Box.

1 Configuring the FRITZ!Box

Click "Telephony" in the FRITZ!Box user interface.
Click "Telephony Devices" in the "Telephony" menu.
Click the (Edit) button for the respective telephone.
Click on the "Telephony Device Features" or "Properties" tab.
Enable the option "Call rejection on busy (busy on busy)".
Disable the option "Call waiting". With ISDN telephones, you must disable the option directly in the ISDN telephone. Refer to the manufacturer of the device for information on how to set it up, for example consult the manual.
Click "Apply" to save the settings.

2 Function not supported by IP telephones and telephones connected to the Mesh Repeater

The "Busy on busy" function is not supported when making calls with IP telephones (for example FRITZ!App Fon) or telephones connected to a Mesh Repeater. If you are using an IP telephone or a telephone connected to a Mesh Repeater to make a call, it is therefore not possible to give the caller a busy signal.