Folk, Someone please explain to me - We have an existing (pots) PBX, which I am interfacing with asterik (elastix) using a digium TDM400P with 2fxs/2fxo configuration. We want the users in the IP cloud to reach the other PBX and vice-varsa using this single extension from the pots pbx. Should I plug the telephone cable of this extension into an fxs or fxo port? Because, logically, I treat it as an "incoming telephone line" to the asterisk? How about a direct analog line from an ADSL splitter? Do I also hook such a cable into the fxo or fxs port? Because ordinarily, this cable would hook into a telephone headset, so can I hook it into fxs? I'm certainly confused..