ZyXEL Communications ISG50 User Manual

 Chapter 1 Introducing the ISG50

ISG50 User’s Guide

Use the ISG50 to provide VoIP and security services. 

All-in-one Application Scenario

• VoIP phones and smartphones can make internal calls and external calls. 
• Least Cost Routing (LCR) dialing rules put calls through the appropriate outbound line. Long 

distance calls (to C in the figure) use VoIP and local calls (to D) use PSTN or ISDN.

• Auto attendant menu systems act as automatic switchboard operators to help route incoming 

calls to the proper extension.

• Customers (like B) use Web services such as Click To Talk, Skype, or Google Voice to call in. 
• Voice mail stores voice messages for users and can also forward them by email. 
• Conference room extensions allow callers from within and outside your organization to join 

conference calls by dialing a conference room extension.

• Use call recording to record all calls for specific extensions or trunks or let users record calls. 
• VLAN and QoS enhance voice quality. 
• Fax  over  IP.
• PSTN or ISDN outbound voice trunks and fax service.

• Firewall protected Internet access and DMZ network for publicly accessible servers.
• IPSec VPN-secured VoIP services and internal server access for teleworkers (A and C in the 

diagram).

• Multiple WAN gives fail-over protection for VPN connections and VoIP.

Use the ISG50 with a USG, ZyXEL’s Unified Threat Management (UTM) firewall to add more security 
services like IDP and anti-virus. If you connect the ISG50 to a USG model’s DMZ, the ISG50