FRITZ!Box 6490 Cable Service - Knowledge Base

FRITZ!Box 6490 Cable Service

Telephone does not ring when you receive a call

One or more of the telephones connected to the FRITZ!Box sometimes do not ring or never ring when you receive a call, although you can make calls.

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

1 Number of calls over a DECT repeater is limited

A maximum of two of the telephones located in the reception area of a DECT repeater from another manufacturer ring when you receive a call. If you are using a FRITZ!DECT Repeater or a FRITZ!Box in DECT repeater mode, up to five telephones can ring at the same time.

2 Disabling the Do Not Disturb setting, call blocks, and call through

The telephone may not ring because Do Not Disturb, a call block, call diversion, or call through is enabled in the FRITZ!Box. Disable these settings in the FRITZ!Box:

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Click the (Edit) button for the respective telephone.
  4. Click on the "Do Not Disturb" tab, disable any "Do Not Disturb" settings, and click "OK".

    Important:Do Not Disturb cannot be set up for IP telephones connected to the "LAN/WLAN" interface, for example FRITZ!App Fon.

  5. Click "Telephony" and then "Call Handling", and delete all call blocks.
  6. Click on the "Call Through" tab. If the tab is not displayed, enable the Advanced View first.
  7. Disable call through and click "Apply".

3 Disabling "DECT Eco"

The following steps are only necessary if the problem occurs with a cordless telephone:

  1. Click "DECT" in the FRITZ!Box user interface.
  2. Click "Base Station" in the "DECT" menu.
  3. Disable the option "DECT Eco" in the section "Radio Field Strength".
  4. Click "Apply" to save the settings.

If the telephone rings now, the DECT connection to the telephone was disturbed. Any devices that emit radio waves could be a source of interference. These include other DECT base stations, baby monitors, mobile telephones, and television antennas, for example. If the telephone does not receive the "wake up" signal from the FRITZ!Box in time and therefore does not wake up from standby mode, repositioning the telephone may help.

4 Connecting the telephone directly to the FRITZ!Box

The following steps are only necessary if the telephone is connected to a PBX (telephone system) that is connected to the FRITZ!Box:

  1. Disconnect the telephone from the PBX and connect it directly to the FRITZ!Box.

If the telephone rings now, the PBX is incorrectly configured. Information on how to configure the PBX can be obtained from the manufacturer.

5 Assigning telephone numbers to telephones

The procedure depends on how the telephone is connected to the FRITZ!Box:

Entering telephone numbers in ISDN telephones

  1. Delete all of the telephone numbers configured in the telephone.
  2. Re-enter the desired telephone numbers in the telephone exactly as they are displayed in the FRITZ!Box user interface in the settings for the telephone on the "FON S0" tab.

    Note:You can find information on configuring the telephone numbers (MSNs) in the telephone's manual, or consult its manufacturer directly.

Assigning numbers to cordless telephones, analog telephones, and IP telephones (such as FRITZ!App Fon)

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Click the (Edit) button for the respective telephone.
  4. Configure the telephone so that it reacts to incoming calls to the desired telephone number: Enter the number under "Outgoing calls" or "Incoming calls", or enable the option "React to all numbers".
  5. Click "OK" to save the settings.

6 Disabling the energy-saving mode for ISDN telephones

The FRITZ!Box is equipped with a number of energy-saving mechanisms. For example, communication between the internal S0 bus and ISDN devices is terminated when there are no active connections. Some ISDN devices have problems with this function. Therefore, disable this function in the FRITZ!Box if ISDN devices are having problems establishing connections:


  1. Configure the telephone so you can send keypad sequences (sequences of characters and numbers, such as *121#) and enter special characters such as * and # with it. On many telephones, you can configure this function in the menu "Operation at a PBX > Dialing options > Dial * and #".

Disabling the energy-saving mode

  1. Enter #966*1* on your telephone and press the call key (pick up the handset).
  2. Hang up again after about 3 seconds.

    Note:You can re-enable this function by entering #966*0*.

7 Having your numbers checked

If the telephone still does not ring when you receive calls to an internet telephone number although the internet connection and internet telephone number were configured correctly, your internet telephony provider is experiencing a problem:

Important:After porting telephone numbers (for example after switching to an IP-based connection), telephone numbers can often be used immediately for outgoing calls. However, you cannot receive calls to these numbers for one or two days because the telephone numbers are not completely ported until then.

  1. Contact your internet telephony provider and have your number checked.