ZyXEL Communications ISG50 User Manual

Chapter 2 Features and Applications

ISG50 User’s Guide

F: SIP Servers - Servers (D) located at your Internet Telephony Service Provider (ITSP) which 
process outgoing calls from the ISG50 and direct them to IP phones on the Internet or traditional 
phones on the PSTN.

SIP Devices and the ISG50 

The ISG50 allows you to set up and manage features on an internal telephone network without 
relying on your telephone service provider. The following are just a few examples: 

• Conference calls
• Voicemail 
• Call Forwarding

The ISG50 integrates with your IP network. For example you can:

• Import an LDAP-based (Lightweight Directory Access Protocol) contact list to serve as the 

phonebook for the IP phones on your network. 

• Set up the ISG50 to send users email notifications or complete voice messages as attachments 

when they receive voicemail. 

The ISG50 can be used stand alone to provide intercom (calling by extension) and VoIP features in 
a small business environment. The ISG50’s capability can be expanded by:

• A - Adding a USB hard disk to store a greater volume of call records.