Simply put, PBX, private branch exchange, is a telephone network within an organization with shared external phone lines to make calls outside the company. Business hosted PBX offers several advantages:
- Decreased expense because each phone does not have to have its own connection to an external line
- Capability to reach coworkers through a three or four digit extension
Centrex is a type of service for those companies using hosted PBX providers, in which the telephone company manages the equipment and sells services for the company to use the PBX, typically along with other services.