ZyXEL Communications ISG50 User Manual

 Chapter 28 Voice Interfaces

ISG50 User’s Guide

performance, monitoring, power transfer, and multiplexing of the channels. You must connect a TE 
device to a NT device to access an ISDN network. The ISG50 is a TE device.

There are many different ISDN switch types from different vendors in the world. The BRI interface 
enables the ISG50 to communicate with the following BRI switches.

• 5ESS - AT&T basic rate switches 
• MDS100
• NI1 - National ISDN-1 switches
• ENT3 - Euro-ISDN switches (UK and others)
• AUS - Australian TS013 switches 

Use this screen to configure settings for the analog phones connected to the ISG50. To access this 
screen, click Configuration > PBX > Voice Interfaces > FXS.

Configuration > PBX > Voice Interfaces > FXS

Each field is described in the following table.

Configuration > PBX > Voice Interfaces > FXS

Tx Volume Level

Select the volume level transmitted from the ISG50. -6 is the quietest, and 6 is the 
loudest. 

Rx Volume Level

Select the volume level transmitted to the ISG50. -6 is the quietest, and 6 is the loudest. 

Dial Interval Sec

Enter the number of seconds the ISG50 should wait after you stop dialing numbers (from 
FXS extensions) before it makes the phone call. 

Country Code

The signals used by telephone companies to indicate a busy line or an available line differ 
by country. You must select the country code for the location of the ISG50. The ISG50 can 
then detect whether the FXS line is in use or available.  Select default to reset the 
country code value to the factory defaults. 

Fax Protocol

Select Pass-Through to use UDP packets with G.711 format or T.38 format to send fax 
messages. T.38 provides better quality, but it may have inter-operability problems. The 
peer devices must also use T.38.