ZyXEL Communications ISG50 User Manual

ISG50 User’s Guide

This chapter gives an overview of the ISG50. It explains the front panel ports, LEDs, introduces the 
management methods, and lists different ways to start or stop the ISG50.

The ISG50 combines an IP PBX with powerful routing and security features. Its flexible 
configuration helps network administrators set up the network and enforce security policies 
efficiently, making it an ideal solution for reliable, secure voice and data service.

An IP PBX is a telephone exchange device located at a company site which allows an organization to 
set up and control calls. IP stands for Internet Protocol, and PBX stands for Private Branch 
Exchange. A regular company telephone switchboard is an example of a PBX. The company’s 
telephones are connected to the IP PBX. The IP PBX is then connected to the outside world via 
connections to a combination of the following networks:

• A traditional Public Switched Telephone Network (PSTN): ISG50-PSTN
• An Internet connection to an Internet Telephony Service Provider (ITSP): all ISG50 models
• An Integrated Services Digital Network/Basic Rate Interface Network (ISDN BRI): ISG50-ISDN 

Each telephone connected to an IP PBX has an extension assigned to it. An extension is a unique 
telephone number within an organization typically consisting of only a few digits. People inside the