You are probably much better off calling AT&T support - from my looking around on their site, CWMX.com with SSL enabled - I have never seen so much trash in getting what really is a simple answer. Call them. As far as DUN, I have been a PDANet user for 6 or so years and suggest that as a simple answer. The link is
http://junefabrics.com/pdanet/index.php.