Two connections are established when making calls with an IP telephone that is configured for the "LAN/WAN" port. Therefore, you can conduct a maximum of four calls at the same time with IP telephones, and the number of possible calls is reduced.

Example:
If you conduct a call with an IP telephone, six additional calls can be made using the other interfaces.
If two IP telephones are being used to conduct calls, four additional calls can be made using the other interfaces.
If four IP telephones are being used to conduct calls, no additional calls can be conducted using the other interfaces.

You can conduct a maximum of three calls at the same time using cordless telephones that are registered with the FRITZ!Box's DECT base station.

Example:
If calls are being conducted with three cordless telephones and an IP telephone, three additional calls can be made using the other interfaces.
If three cordless telephones and two IP telephones are being used to conduct calls, one additional call can be conducted using the other interfaces. You cannot conduct an additional call with an IP telephone.

You can conduct one call with an analog device connected to the socket "FON".

The answering machine and the fax can each accept one call. All other callers hear a busy signal, even if you set up more than one answering machine. You cannot send a fax while receiving a fax, and you cannot receiving a fax while sending one.