A private branch exchange (PBX) is a telephone exchange or switching system that serves an organization and performs concentration of central office lines or trunks and provides intercommunication between a large number of telephone stations in the organization.

A wireless home security systems is better than the traditional system in many ways. First, it does not require any installation that might cost more than the gadget itself. The setup is simple to use, so contractors would not be needed anyhow. There would be no wirings involved, so it means the fewer risks. Wireless security systems for homes can either be battery-operated or power outlet-dependent. Bear in mind that battery-operated ones are better used when blackouts are frequent; however, the batteries could be costly. Wireless intercom system that rely on power outlets are cheaper and have the same efficiency as a battery operated ones.