I think you actually need 1 FXS and 1 FXO. What has to happen is that the local PSTN line needs to be plugged in to the FXO at your home. The unit then has to be configured to answer the ringing line automatically and PLAR ( hotline ) the call to a unit that you specify ie. the FXS which has a standard analog phone plugged in to it. To get the other way around, ie get local dialtone from overseas, you need to set up the FXS to PLAR ( hotline ) to the FXO and all is done. Any questions?