Draytek FXS4P voice network module

FXS4P - Analogue FXS Module The FXS module provides 4 ports for connection of up to four analogue phones. Each phone is then an additional extension on the PBX, with its own extension number, voice mailbox etc, just like your IP extensions. Instead of a phone, you can connect these FXS ports to the trunk inputs of an existing analogue PBX. That would provide VoIP integration with your existing PBX if you're not ready to replace it just yet.