FRITZ!Box 7369 Service - Knowledge Base
Transmitting a different outgoing caller ID when making calls
Either your internet telephony provider or your landline telephony provider is responsible for transmitting your caller ID, depending on how the call is established. This means that you cannot configure the FRITZ!Box to transmit an outgoing caller ID that differs from the actual number used to make the call. This is why you cannot transmit a landline number instead of your internet number or vice versa, for example. However, when you make a call, you can make an exception and use a different number for the call.
Note:It may also be possible to have your internet telephony provider display a different number when you make internet calls. Refer to your internet telephony provider for information on whether this is possible.