FRITZ!Fon MT-F Serwis - Baza wiedzy

FRITZ!Fon MT-F Serwis
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Parties cannot hear each other

One of the following issues sometimes or always occurs when you conduct calls. It either occurs right at the beginning of the conversation or sometime during the conversation, for example after five minutes:

  • You do not hear the other party.
  • The other party does not hear you.
  • The parties cannot hear each other.

This may give the impression that the telephone connection has been terminated. However, the connection is still active. You can see that it is because the telephony LED on the FRITZ!Box remains lit. The LED does not turn off until you end the call by hanging up.

Note:The configuration procedure and notes on functions given in this guide refer to the latest FRITZ!OS for your FRITZ!Box.

Simply proceed as described below. After each measure, check whether the issue persists.

1 Installing the latest software

2 Entering a STUN server

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephone Numbers" in the "Telephony" menu.
  3. Click the button (Edit) for the respective internet telephone number.
  4. Check whether the field "STUN server" is shown under the fields for entering your account information.
  5. If the field is shown and empty, enter the address of your internet telephony provider's STUN server and click "OK".
    • If the field is not shown:
      1. Select "Other provider" from the drop-down list, even if you are using a preconfigured internet telephony provider.
      2. Check whether the "STUN server" field is now shown.
      3. If the field is shown, enter the address of your internet telephony provider's STUN server and click "OK".
        • If the field is not shown, click "Cancel". The STUN server is preconfigured.

3 Setting up port forwarding for internet telephony

The following steps are only necessary if the FRITZ!Box does not establish its own connection to the internet, but instead shares the internet connection of another router in the network:

Setting up automatic port forwarding

If you enable port forwarding in the FRITZ!Box, then the FRITZ!Box sends IP packets on a regular basis and the router's port forwarding automatically remains enabled:

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephone Numbers" in the "Telephony" menu.
  3. Click on the "Line Settings" tab.
  4. Click on "Change connection settings" in the "Telephony connection" section. If the section is not displayed, enable the Advanced View first.
  5. Enable the option "Keep port forwarding of the internet router enabled for telephony".
  6. Select a suitable time interval. Select "30 seconds" if you do not know how long temporary port forwarding rules are maintained.
  7. Click "Apply" to save the settings.

Setting up static port forwarding

The following step is only necessary if the router does not support automatic port forwarding via the FRITZ!Box:

Note:Refer to the manufacturer of the router for information on how to set it up, for example consult the manual.

  1. On the router, configure static port forwarding from any UDP ports >= 1024 (for example 6078-6097) to ports 7078-7109 on the FRITZ!Box.
  2. On the router, configure port forwarding from UDP port 5060 to port 5060 on the FRITZ!Box.

The FRITZ!Box is now completely configured for making and receiving calls over the internet. We are not aware of any further measures for this issue. If the issue persists, your internet telephony provider may be experiencing technical difficulties or the router that establishes the internet connection may not be forwarding voice packets to the FRITZ!Box. In these cases, the FRITZ!Box cannot resolve this issue.