Da Voismart Knowledge Base.
Executes dialplan application

Usage: Exec(appname(arguments))
  Allows an arbitrary application to be invoked even when not
hardcoded into the dialplan.  If the underlying application
terminates the dialplan, or if the application cannot be found,
Exec will terminate the dialplan.
  To invoke external applications, see the application System.
  If you would like to catch any error instead, see TryExec.