ZyXEL Communications ISG50 User Manual

ISG50 User’s Guide

This information is provided to help you configure the ISG50 effectively. Some of it is helpful when 
you are just getting started. Some of it is provided for your reference when you configure various 
features in the ISG50.

•

 introduces the ISG50’s object-based configuration.

•

 introduces zones, interfaces, and port groups.

•

 introduces some terminology and organization for the ISG50.

•

 covers the ISG50’s packet flow.

•

 identifies the features you should configure before and after you 

configure the main screens for each feature. For example, if you want to configure a trunk for 
load-balancing, you should configure the member interfaces before you configure the trunk. After 
you configure the trunk, you should configure a policy route for it as well. (You might also have to 
configure criteria for the policy route.)

•

 identifies the objects that store information used by other features.

•

 introduces some of the tools available for system management.

This chapter is an overview of different logical components and how they work together to route 
calls on the ISG50. 

The two main functions of any IP-PBX are routing internal calls and handling calls to and from the 
outside world. 

The following sections explain how these functions are performed on the ISG50.

The following are some terms related to ZyXEL’s IP-PBX implementation.

• Extension - This is a unique number assigned to each telephone connected to the ISG50. 

Extensions are used to make calls between phones connected to the ISG50 and to route calls 
from the outside world to their correct target. Extensions fall into the following two groups:

• SIP Extension - This is an extension assigned to a SIP (Session Initiation Protocol) based IP 

phone connected to the ISG50. Alternatively this could be an extension assigned to an analog 
phone which connects to the ISG50 via a VoIP gateway device.