What Are Groups and Enterprises?
The central exchange (Centrex), which is also called group, is a function of telephone exchange. The Centrex groups some users on a private branch exchange (PBX), and provides various functions of a user-specific exchange and other special services and functions to the user group. A user group does not have a dedicated exchange. The internal and external switching of users takes place inside the telephone exchange. Therefore, the Centrex is also called central user exchange or virtual user exchange.
The group function is not only applicable to enterprises or departments with lots of employees, but also applicable to scenarios in which user extensions are widely dispersed. The group function provides flexible networking, and makes it easy to increase or decrease network capacity. Enterprises and departments that use the group function can enjoy specialized services in addition to services on the Public Switched Telephone Network (PSTN).
Group users have two numbers. One is an internal number which is called the private number. The other is an external number which is called the long code. Users in the same group can dial private numbers to call each other. The private numbers have the highest priority. Users inside a group dial private numbers by default. If a user inside a group wants to call an external user, the user must first dial the call prefix of the group that the external user belongs to. The group ID is an important property of group users. You must specify the group ID to configure group users or modify group properties.
The range of the enterprise function is larger than that of the group function. A group can only belong to an enterprise. Users inside an enterprise can belong to any groups, or not belong to a group. Users inside an enterprise can call each other, but cannot call users of another enterprise.
The group and enterprise functions group users on the service layer. The DN set function groups numbers on the switch layer.