ZyXEL ISG50-PSTN User Guide - Page 27

CHAPTER 1 Introducing the ISG50 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. 1.1 Overview 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. 1.1.1 PBX 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 ISG50 User's Guide 27