What is FXO and FXS and why is it important when using an IP PBX?
Very clear explanation by a trusted partner. FXS, FXO explained | 3CX VoIP blog http://www.3cx.com4/3/06 What is FXO and FXS and why is it important when using an IP PBX? This article explains what FXO & FXS are and how they work.