What is pbx machine?

A PBX (Private Branch eXchange) is a small telephone switch owned by a company or organization. These organizations purchase PBX's to reduce the total number of telephone lines they need to lease from the telephone company. Without a PBX, a company will need to lease one telephone line for every employee with a telephone.With a PBX system, the company only needs to lease as many lines from a telephone company or telecommunication provider as the maximum number of employees that will be making outside calls at one time. This is usually around 10% of the number of extensions.In a PBX system, every telephone is wired to the PBX. When an employee takes the receiver off hook (i.e. picks up the telephone) and dials the outside access code (usually 9), the PBX connects the employee to an outside line (often, though somewhat incorrectly, referred to as a trunk).