ZyXEL Communications ISG50 User Manual

Chapter 8 PBX Tutorials

ISG50 User’s Guide

You can now use the telephones that are part of the Basic authority group to make long distance 
calls using the ITSP connection. The following figure summarizes the outbound call process for this 
example.   

The following section shows you how to make and receive calls via a connection to the ISDN. This 
example covers:

•

 - configuring the outbound line group’s connection settings from the BRI 

interface to the ISDN.

•

 - creating a rule which tells the ISG50 when to use the ISDN 

connection when completing outbound calls.

•

 - giving extensions the right to make outbound calls via 

the ISDN connection. 

Making an ISDN Call

Caller dials 
1212555555

The ISG50 matches this number
with the long_distance_call LCR,

applies the offset (strips off the 1), 

of the number and routes the call 
to ITSP.

sends the call 
016212555555.

The ISG50 

adds the prefix 016 to the start of   

and sends the call 
to 212555555.

The ITSP applies
the dialing plan rate

Caller dials 
8005555555

The ISG50
matches this number 
with an LCR, routes the
call to ISDN.