Recommend us:
To the knowledge base

Configuring an ISDN telephone in the FRITZ!Box

You can connect one or more ISDN telephones to the "FON S0" socket of the FRITZ!Box. The telephones and the FRITZ!Box only have to be configured for parallel use.

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

1 Configuring telephone numbers in the FRITZ!Box

Configure all of your telephone numbers in the FRITZ!Box:

  1. Configure the internet telephone numbers in the FRITZ!Box.

2 Connecting the telephone to the FRITZ!Box

  1. Connect the telephone to the "FON S0" socket on the FRITZ!Box.

    Note:If you want to use both S0 buses on the FRITZ!Box, use the adapter included with delivery. You can connect up to eight ISDN telephones or one ISDN telephone system to each bus, but the FRITZ!Box can only supply one telephone with power.

3 Configuring a telephone in the FRITZ!Box

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Click the "Configure New Device" button.
  4. Enable the option "Telephone (with or without answering machine)" and click "Next".
  5. Enable the option "FON S0 (ISDN telephone)", click "Next", and follow the instructions. A wizard takes you through the configuration.

4 Entering your telephone number in the telephone

If the telephone does not react to the desired telephone numbers after the configuration is completed, re-enter the numbers in the telephone:

  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.

5 Setting up the FRITZ!Box for incoming calls

Regardless of which ISDN devices you connected to the "FON S0" sockets, you must use keypad sequences to set up the FRITZ!Box for incoming calls:

Preparations

  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 #".

ISDN telephones on both sockets

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

Telephone system for a BRI and ISDN telephones

  1. Enter #965*2*#966*3* on the telephone and press the call key (pick up the handset).
  2. Hang up again after about 3 seconds.