Da Voismart Knowledge Base.
Executes dialplan application, always returning

Usage: TryExec(appname(arguments))
  Allows an arbitrary application to be invoked even when not
hardcoded into the dialplan. To invoke external applications
see the application System.  Always returns to the dialplan.
The channel variable TRYSTATUS will be set to:
    SUCCESS   if the application returned zero
    FAILED    if the application returned non-zero
    NOAPP     if the application was not found or was not specified