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WiMAX Device Configuration User’s Guide 171
CHAPTER 11
The VoIP Line Screens
11.1 Overview
The features mentioned in this chapter are for models with VoIP function.
The VoIP > Line 1 (or Line 2) screens allow you to configure the volume, echo cancellation, VAD
settings and custom tones for the phone port which maps to the SIP account (see Chapter 10 on
page 157).
Note: If your WiMAX Device has only one phone port, there is only one line.
Note: You can identify the number of phone ports available on your WiMAX Device by its
model name. See Section 1.1 on page 17 for more information.
11.1.1 What You Need to Know
The following terms and concepts may help as you read through this chapter.
Voice Activity Detection/Silence Suppression/Comfort Noise
Voice Activity Detection (VAD) detects whether or not speech is present. This lets the WiMAX Device
reduce the bandwidth that a call uses by not transmitting “silent packets” when you are not
speaking.
When using VAD, the WiMAX Device generates comfort noise when the other party is not speaking.
The comfort noise lets you know that the line is still connected as total silence could easily be
mistaken for a lost connection.
Echo Cancellation
G.168 is an ITU-T standard for eliminating the echo caused by the sound of your voice
reverberating in the telephone receiver while you talk.