A boom barrier, also known as a boom gate, is a bar or pole that pivots to prevent vehicular or pedestrian access at a controlled point. Boom barriers cannot be moved and must be installed in a specific location. 

It is a stand-alone intercom system used to manage calls with access controlled by audio- visual communication between the inside and outside. 

An electronic systems that allow authorized personnel to enter a security portal without a security officer reviewing and validating their authority

 EPABX is an electronic device used in Offices, Industries and many other places for voice communication. 

It is independent and can work with out any trunk lines.