ON 20110202@7:39:15 AM at page: On a web page you were interested in at: http://techref.massmind.org/Techref/pots/dtmf.htm# David A Cary[DAV-MP-E62a] edited the page. Difference: http://techref.massmind.org/techref/diff.asp?url=\Techref\pots\dtmf.htm&version=0