ZyXEL Communications ISG50 User Manual

Chapter 34 Call Services

ISG50 User’s Guide

Call waiting allows you to put a present call on hold and answer a new call. When a second call 
comes in, the ISG50 sends a beep tone to you. You can decide to ignore it or to switch to the 
second call using one of the following methods.

• press the flash button on your telephone
• very quickly press and release the on-hook switch on your telephone

You can switch back to the first call using the same methods above. When you hang up one call, the 
ISG50 sends you a ring tone if another call is still waiting. 

Note: This feature only applies to extension receivers which use SIP or analog phones.

The following figure shows how call waiting works.

Call Waiting Overview

Call Waiting Example

1. Caller A makes a 

call to caller B.

2. The ISG50 routes the call 

to B at extension 1001.

3. B picks up the call.

4. Conversation established between caller A and B

5. Caller C 

makes a call 
to caller B.

6. The ISG50 routes the call 

to B at extension 1001.

7. B hears a beep tone and decides 

to answer the second call. B then 
presses the flash button on his 
telephone).

8. Conversation established between caller C and B. Caller A is on hold. B is busy.