The phone system, traditionally known as a EPBX (Private Branch Exchange,) provides communication services based on the capacity of the users, and the business user can select the proper EPBX which contains different features along with inter come of call transferring capacity like auto-attendant.
The EPBX sits between the users of an organization and the phone company, which allow the organization to work more efficiently than normal telephone on their desk.
The EPBX is a small telephone switch installed by a company or organization. It is an internal exchange. EPBX's reduce the total number of telephone lines they need to lease from the telephone company. It is not possible to setup an internal telecom system without an EPBX; otherwise the company needs more than one lease line for their employee.
The company needs to purchase or lease as many lines from the telephone company as the maximum number of employees that will be making outside calls at one time. In an EPBX system, every telephone is wired to the EPBX.