The following DECT devices for telephony can be registered with the FRITZ!Box at the same time:

• six cordless telephones / DECT headsets / DECT door intercom systems (total)
• six FRITZ!DECT Repeater 100

You can register up to ten IP telephones (for example FRITZ!App Fon) or IP door intercom systems with the FRITZ!Box.

The FRITZ!Box has three sockets for analog devices. You can use two of them, for example for a telephone, fax machine, and/or door intercom system. One "FON 1" socket must remain free (unassigned):

• "FON 1" and "FON 2" for devices with an RJ11 plug
• "FON 1" for devices with a TAE plug

You can use an ISDN distributor or S0 bus cabling to connect up to eight devices, for example a telephone or telephone system, at the same time to the "FON S0" socket on the FRITZ!Box. The FRITZ!Box can provide power to one ISDN device, but the other ISDN devices must use their own power supply. Not every FRITZ!Box model has a "FON S0" socket.

You can use the following ISDN service indicators with devices connected to the "FON S0" socket:

• Voice (service indicator 1)
• Data (service indicator 2)
• Audio 3.1 (service indicator 4)
• Telephony (service indicator 16)
• Fax G2/G3 (service indicator 17)

You can use the FRITZ!Box as a fax and answering machine, without having to connect any additional devices. The FRITZ!Box can be used to send and receive faxes and you can configure up to five different answering machines.