FRITZ!Fon C4 Service - Knowledge Base

FRITZ!Fon C4 Service

Suppressing your telephone number

You can suppress your telephone number when making calls so that it is not transmitted to the party you are calling. That way the party you are calling does not see your number in the display of their telephone. This function is called "CLIR" (Calling Line Identification Restriction). You can either suppress your caller ID for a single call or permanently suppress it for all calls.


  • The FRITZ!Fon must be registered with a FRITZ!Box.
  • Your telephony provider must have enabled Calling Line Identification Restriction (CLIR) on a call-by-call basis for your telephone line.

1 Suppressing the number on a case-by-case basis (for a single call)

You can suppress your caller ID for a single call. Your caller ID will be transmitted again when you make subsequent calls:

  1. Press the "Menu" key on the telephone.
  2. Scroll to "Settings" and press "OK".
  3. "Telephony" > "OK" > "Anonymous call" > "OK"
  4. Enable the option "Next call".
  5. Press the "end call" key.

2 Permanently suppressing your caller ID (for all calls)

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Click the (Edit) button for the respective telephone.
  4. Click on the "Telephony Device Features" tab.
  5. Enable the option "Calling line identification restriction (CLIR)".
  6. Click "OK" to save the settings.