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Knowledge document #1710

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.

Requirements / Restrictions

  • A maximum of eight ISDN telephones can be connected to the FRITZ!Box.
  • The ISDN telephones must be suitable for use on an ISDN point-to-multipoint line.

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

1 Installing the latest FRITZ!OS for the FRITZ!Box

  1. Install the latest FRITZ!OS on the FRITZ!Box.

2 Configuring telephone numbers in the FRITZ!Box

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

Configuring internet telephone numbers

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

Configuring landline numbers

  1. Configure the landline number in the FRITZ!Box.

Configuring a mobile telephone number

  1. Configure your mobile telephone number in the FRITZ!Box.

3 Connecting the telephone to the FRITZ!Box

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

    Note:You can connect several ISDN telephones to the FRITZ!Box, but the FRITZ!Box can only supply one telephone with power. All others need their own power supply.

4 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.

5 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.

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