Editor’s Note: This article was originally posted in October 2015 and has been fully updated for accuracy and comprehensiveness in June 2018. If you are researching into deploying a VoIP Telephony System on your own for the first time, you are probably seeing FXS and FXO acronyms all over the place.  When you’re new to … Continue reading What are FXS and FXO ports? What are they used for?