This is an optional PC Board to replace the TELCO module inside an AIRMATE-USB
To be able to use Voice over IP (VoIP) instead of landlines (POTS).
This VoIP module also provides you with a Cleanfeed output to send a mix minus signal to an external Hybrid in case a land line is still needed. The Hybrid can return its signal to the line input of the VoIP module. You can replace one or both TELCO modules if you like.Some knowledge of electronics is necessary to perform this switch.