Hello All, This is bit obtuse. Does someone here know where I could find some reference documents for the audio performance of an FXS port? I've found old Belcore docs that have all kinds of detail in signaling behavior, but nothing about the in-band audio performance. What I'm seeking is to determine if there remains a specific standard that determines the usable passband. Many thanks, Michael Graves mgraves at mstvp.com http://www.mgraves.org o(713) 861-4005 c(713) 201-1262 sip:mgraves at mjg.onsip.com skype mjgraves