check to make sure the extension exists b4 actually accepting the call and...

check to make sure the extension exists b4 actually accepting the call and lets hope this gives Open H.323 enough time to sync up (bug #1714)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@3220 65c4cc65-6c06-0410-ace0-fbb531ad65f3