Merging from 1.2, bug 5925 - app_voicemail should check for the callerid it sets for unknown

Also, remove unnecessary res checks (initialized to 0; never set)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@7313 65c4cc65-6c06-0410-ace0-fbb531ad65f3