Understanding FXO and FXS ports – DRBIG Corner of the net

FXO ports connect to the PSTN network (Telephone Line). VoIP Adapters will have either none or 1 FXO port.

Having an FXO port on the adapter will allow you to switch between making/receiving VoIP calls over the Internet and calls over the conventional phone line.

FXS ports connect to analogue phones or fax machines. VoIP adapters range from 1 or 2 FXS ports.

2 FXS ports for example would allow you to have 1 Cordless DECT phone and one fax machine connected to the VoIP adapter or 2 phones each with their own VoIP line.