ZyXEL Communications max208m User Manual

Chapter 9 The VoIP General Screens

WiMAX Device Configuration User’s Guide

This section describes the features of the Quality of Service (QoS) screen.

Click VoIP > General > QoS to set up Type of Service (ToS) and Differentiated Services (Diffserv) 
settings for voice traffic transmission through the WiMAX Device.

QoS

The following table describes the labels in this screen.

Packet Loss 
Concealment

Packets may be dropped due to an overwhelming amount of traffic on the 
network. Some degree of packet loss will not be noticeable to the end user, but 
as packet loss increases the quality of sound degrades. Select this to have the 
WiMAX Device to improve the voice quality when packet loss occurs.

T.38 Static Jitter 
Length

T.38 is an ITU-T standard that VoIP devices use to send fax messages over the 
Internet.

Select the number of milliseconds for the jitter buffer size used for transmitting 
T.38 fax messages.

Media (continued)

QoS

SIP ToS/DiffServ

Enter the DSCP value you want to mark on all outgoing SIP packets generated by 
the WiMAX Device for DiffServ-enabled networks. Since DiffServ uses the first 6 
bits of the 8-bit IP ToS field to represent the DSCP value, enter here the 6-bit 
DSCP value you want to mark in hexadecimal (in a format of 0x00), and the 
WiMAX Device will then automatically append 2 bits '0' to make a whole 8-bit 
ToS field value for all outgoing SIP packets. 

For example, if you enter 0x2E, it is 101110 in binary for DSCP. The WiMAX 
Device converts it to 10111000 in binary and marks on the IP ToS field of all the 
outgoing SIP packets.

RTP ToS/DiffServ

Enter the DSCP value you want to mark on all outgoing VoIP data packets 
(including both RTP and T.38 UDPTL packets) generated by the WiMAX Device for 
DiffServ-enabled networks.