The basic function of the PBX telephone system is to connect the internal and external communication networks of the company. It does this by routing calls to multiple office extensions and phones.

The PBX phone system is also connected to the public switched telephone network (PSTN), SIP trunks, and VoIP providers.

The PBX system requires hardware and software and consists of a telephone line, a computer with memory, a line network, and a console or switchboard.

All of these have been integrated to create an effective communication system. The traditional PBX is cable-based and its function depends on the actual hardware box. Ideal for offices with 50 or more employees.