ZyXEL Communications ISG50 User Manual

Chapter 30 Outbound Trunk Group

ISG50 User’s Guide

This example also shows three call examples. 

A - When an outsider calls 555-123457, the call is mapped to the extension 1111. 

B - When someone makes an outgoing call from the extension 1111, the caller ID shown to the 
callee is 555-123457. 

C - When you make a call over this outbound line from an extension that is NOT listed in the DDI 
mapping table, the directory number (555123456 in this example) is the number that displays on 
the callee’s caller ID. 

Note: Calls on incoming ISDN numbers that are not included in the DDI mapping table go 

to the AA.

ISDN calls can be made directly to an extension number from another PBX that is connected 
directly. In this example, all incoming calls are forwarded to the extension called.

Direct Example 

This feature is relevant to ISDN BRI (TE mode) only. In this example, two ISG50s use a BRI hub to 
share a single BRI line to one TSP (Telecommunications Service Provider). Each ISG50 can have up 
to 10 BRI trunks for each BRI line it uses. Each BRI trunk uses a unique MSN. This example uses 20 
MSNs for the single BRI line. These MSNs must correspond to those configured on the connected 
TSP’s ISDN device. Device A’s auto-attendant system answers the incoming call only when the 
number matches the MSN configured on device A.

MSN Example 

6012

6012

ISDN BRI

TE mode

Please 

extension!

dial 

NT mode

TE mode

MSN1 : 555-100001

MSN10: 555-100010

BRI Hub

MSN11 : 555-200001

MSN20: 555-200010

MSN1 : 555-100001 ~ MSN10: 555-100010

MSN11 : 555-200001 ~ MSN20: 555-200010