I can make calls from a phone connected to FRITZ!Box, but I cannot receive calls. What can I do?

There may be various reasons why an analog phone on a FRITZ!Box extension does not ring for incoming calls, although you can use it to call out. To determine the exact cause, carry out the following steps in sequence. After each step, test whether the telephone rings for an incoming call.
  1. Make sure FRITZ!Box is correctly connected to your telephone line. Connect the ISDN/analog socket on FRITZ!Box
    • to the network terminator (NT) of your ISDN line
      • or
    • to the phone jack on your ADSL splitter, if you have an analog phone line. Use an eight-lead cable (such as the ISDN/analog cable included with your FRITZ!Box) and the black RJ11 adapter supplied.
  2. In your web browser, open the FRITZ!Box user interface.
  3. Click on "Settings".
  4. "Telephony" > "Extensions"
    or
    "Advanced Settings" > "Telephony" > "Telephony Devices"
  5. Click on the "Edit" icon for the extension that the telephone is connected to (FON 1 or FON 2).
  6. If available, click the "Extension Properties" tab.
    • Under "Which terminal device is connected to the extension? " select "Telephone" and click "Apply".
    • Click the "Extension" tab.
  7. Activate the option "React to all numbers", and click "Apply".
    If the telephone now rings, then the configuration window for this extension contains only telephone numbers that do not correspond to your phone line. Enter the correct numbers for your telephone line, then deactivate the option "React to all numbers", and click "Apply". For information on setting the phone numbers, see the configuration page's online Help.
  8. Check whether the cable connecting FRITZ!Box to the phone jack on the ADSL splitter or the ISDN NT is damaged. Try replacing the cable with the red network cable supplied with FRITZ!Box.