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

Example:
If you conduct an internet call with an IP telephone, three additional internet calls can be made using the other interfaces.
If an IP telephone is being used to conduct an internet call and another IP telephone is used for a landline call, two additional internet calls can be conducted with the other interfaces.
If two IP telephones are being used to conduct internet calls, one additional internet call can be conducted using the other interfaces.

You can conduct a maximum of three calls from your landline and/or over the internet at the same time using cordless telephones that are registered with the FRITZ!Box's DECT base station.

Example:
If internet calls are being conducted with three cordless telephones and an IP telephone, you cannot conduct an additional internet call using the other interfaces.

One call can be conducted with each of the analog devices connected to the socket "FON 1" or "FON 2".

A maximum of two calls can be conducted at the same time from the landline and/or the internet using ISDN devices connected to the "FON S0" socket.

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.