Businesses in the alarms and signalling equipment category supply, install and maintain systems that alert people to hazards, security risks or operational events. Equipment may include intruder and fire alarm panels, detectors, sensors, sounders, sirens, flashing beacons, call points and control units. Some suppliers also provide emergency call systems, door-entry alarms and signalling equipment for workplaces, public buildings or industrial sites. Services can include assessing a site's needs, designing a system, fitting and connecting equipment, and integrating it with other building or security systems. Customers may also expect testing, fault diagnosis, repairs, replacement parts and routine servicing. The type of equipment and installation requirements depend on the setting and the purpose of the system, such as detecting smoke, alerting staff to a machine fault or notifying occupants that an emergency response is needed.