In the event anyone else happens to run into this... We upgraded voicemail pro and moved it from a 2003 server to a 2012 server. The fresh install of Voicemail Pro was installed as an administrator , the service was running as an administrator and we could not access the Web Campaign through the new 2012 server. We received a HTTP 500 error. IIS was installed, the asp.net was disabled. The fix was to edit the security permissions for the voicemail pro folder and add "everybody" under groups or user names with full permissions. (We probably could have tried the Campaign folder but I was just happy we got it working.)