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Since update, internet telephone numbers from Deutsche Telekom no longer registered

The FRITZ!Box is being used behind a Speedport Hybrid. Since updating FRITZ!OS, the internet numbers from Deutsche Telekom are no longer registered in the FRITZ!Box.


  • To allow the use of Deutsche Telekom's "CompanyFlex" plan, the new FRITZ!OS takes the provider's NAPTR record into account, which redirects the transport protocol of the internet telephone numbers to TLS.

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

1 Switching the Telekom internet telephone number to UDP in FRITZ!Box

The following step is only necessary if the internet telephone number does not belong to a SIP trunk from Deutsche Telekom:

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephone Numbers" in the "Telephony" menu.
  3. Click the (Edit) button for the Telekom internet telephone number.
  4. Select "Other provider" from the "Telephony provider" drop-down list.
  5. In the section "Additional Settings for the Connection", select "UDP" from the drop-down list "Transport protocol".
  6. Click "OK" to save the settings.