\Registry\machine\software\microsoft\fax\Routing Extensions
    FaxSiren Routing Extension
        FriendlyName = Fax Siren 
        ImageName = REG_EXPAND_SZ %systemroot%\system32\faxsiren.dll
        Routing Methods
            Siren
                FriendlyName = Routing Siren
                Function Name = RouteIt
                Guid = {5797dee0-e738-11d0-83c0-00c04fb6e984}