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)