This standard specifies in addition to the requirements specified in EN 50136-2-1, the requirements for equipment used in alarm transmission systems utilising dedicated alarm transmission paths. The alarm transmission system utilise wired links (e.g. d.c. or a modulated signal over a twisted pait cable), voice grade signalling links or data ilnks and may include multiplexers or message processors. The standard is also applicable to alarm transmission systems in which signalling links are shared with other services. Such services include normal subscriber telephone line from the supervised premises to the local exchange, cable TV or power distribution networks, but is equally applicable to other systems.