Editing Security alarm (section)

==Alarm connection and monitoring==
Depending upon the application, the alarm output may be local, remote or a combination of both.  Local alarms do not include monitoring, but may include indoor and/or outdoor sounders, such as motorized bells or electronic sirens and lights, such [[strobe light]]s which may be useful for signaling an evacuation notice during fire emergencies, or to scare off an amateur burglar quickly.  However, with the widespread use of alarm systems, especially in cars, false alarms are very frequent and many urbanites tend to ignore alarms rather than investigating, and not contacting the necessary authorities. In rural areas where not many may hear the fire bell or burglar siren, lights or sounds may not make much difference, as the nearest emergency responders may arrive too late to avoid losses.

Remote alarm systems are used to connect the control unit to a predetermined monitor of some sort, and they are available in many different configurations. Advanced systems connect to a [[alarm monitoring center|central station]] or first responder (e.g. police/fire/medical) via a direct phone wire, a cellular network, a radio network, or an IP path. In the case of a dual signaling system two of these options are utilized simultaneously. The alarm monitoring includes not only the sensors, but also the communication transmitter itself. While direct phone circuits are still available in some areas from phone companies, because of their high cost and the advent of dual signaling with its comparatively lower cost, their use is being phased out. Direct connections are now most usually seen only in federal, state, and local government buildings, or on a school campus that has a dedicated security, police, fire, or emergency medical department. In the United Kingdom, communication is only possible to an alarm receiving centre, and communication directly to the emergency services is not permitted.

More typical systems incorporate a digital cellular communication unit that will contact the central station or a monitoring station via the [[public switched telephone network|Public Switched Telephone Network]] (PSTN) and raise the alarm, either with a synthesized voice or increasingly via an encoded message string that the central station decodes. These may connect to the regular phone system on the system side of the [[demarcation point]], but typically connect on the customer side ahead of all phones within the monitored premises so that the alarm system can seize the line by cutting-off any active calls and call the monitoring company if needed. A dual signaling system would raise the alarm wirelessly via a radio path or cellular path using the phone line or broadband line as a backup overcoming any compromise to the phone line. Encoders can be programmed to indicate which specific sensor was triggered, and monitors can show the physical location of the sensor on a list or even a map of the protected premises, which can make the resulting response more effective.

Many alarm panels are equipped with a backup communication path for use when the primary PSTN circuit is not functioning. The redundant dialer may be connected to a second communication path, or a specialized encoded [[mobile phone|cellular phone]], radio, or internet interface device to bypass the PSTN entirely, to thwart intentional tampering with the phone lines. Tampering with the line could trigger a supervisory alarm via the radio network, giving early warning of an imminent problem. In some cases a remote building may not have PSTN phone service, and the cost of trenching and running a direct line may be prohibitive. It is possible to use a wireless cellular or radio device as the primary communication method.

In the UK, the most popular solution of this kind is similar in principle to the above but with the primary and backup paths reversed. Utilizing a radio path as the primary signaling path is not only quicker than PSTN but also allows significant cost savings as unlimited amounts of data can be sent at no extra expense.