Basically all digital PABX has the same functional group, but these functions are applied and arranged in different paths in various systems. PABX function as a telephone connection system to regulate the telephone communication connection process.
The way PABX works, this device is a modem that functions as a central control station. Every time a new phone arrives, the telephone will be routed (directed) through this control station. Because the PABX system has entered a specific code for each telephone number in the office, or for each extension, the incoming call will be directed to the right destination using the code.