ZyXEL Communications ISG50 User Manual

ISG50 User’s Guide

This chapter shows you how to configure dialing rules, also referred to as LCR (Least Cost Routing) 
on the ISG50. 

The following figure shows an example of two LCRs. LCR1 is composed of outbound line groups 
PSTN and ISDN along with the dial condition 01. (the period (.) is part of the dial condition). LCR2 
is composed of outbound line group ITSP along with the dial condition 02.. When a user calls 
“021234” the call is routed through the outbound line group defined in LCR2.

LCR Components Example 

When an LCR contains more than one outbound line group, as in the LCR1 example, the 
administrator can prioritize the outbound line groups in the LCR. When a call is made using an LCR 
with multiple outbound line groups, the ISG50 tries to use the higher priority outbound line group 
first and, if the line is not available, then it tries a lower priority outbound line group.

The following figure shows a possible assignment of LCRs to authority groups. In our example, the 
Sales authority group has been associated with both LCR1 and LCR2, so extensions that are part 
of Sales can use any outbound line group they choose. The second authority group - Research, 

PSTN 

ISDN 

 ITSP