Closed-circuit television (CCTV) is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors.
It differs from broadcast television in that the signal is not openly transmitted, though it may employ point to point (P2P), point to multipoint, or mesh wireless links. Though almost all video cameras fit this definition, the term is most often applied to those used for surveillance in areas that may need monitoring such as banks, casinos, airports, military installations, and convenience stores. Videotelephony is seldom called "CCTV" but the use of video in distance education, where it is an important tool, is often so called.
An alarm device or system of alarm devices gives an audible or visual alarm signal about a problem or condition.
Alarm devices include:
3G Video camera is a perfect combination between alarm system and CCTV Surveillance system. It has built-in camera for video recording and transmitted by 3G to cell phone and also can work with wireless sensors, such as PIR Sensor, Door contact and wireless smoke/gas sensors.