What method does the Zap MWI use? FSK, 48 volt, or 90 volt? --Eric -- Go to http://www.digium.com/index.php?menu=documentation and look at the "Unofficial Links" section. This section has links to a wide variety of 3rd party Asterisk related pages. My page is the "Asterisk Resource Pages". BTEL Consulting 504-899-1387 or 850-484-4545 or 877-677-9643