ZyXEL Communications NVG2053, User Manual

Page: 191 / 200

Chapter 17 Voice
NVG2053 User’s Guide
191
Comfort Noise Generation
When using VAD, the NVG2053 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.
MWI (Message Waiting Indication)
Enable Message Waiting Indication (MWI) enables your phone to give you a
message–waiting (beeping) dial tone when you have a voice message(s). Your
VoIP service provider must have a messaging system that sends message waiting
status SIP packets as defined in RFC 3842.
17.9.1 Quality of Service (QoS)
Quality of Service (QoS) refers to both a network's ability to deliver data with
minimum delay, and the networking methods used to provide bandwidth for real-
time multimedia applications.
Type of Service (ToS)
Network traffic can be classified by setting the ToS (Type of Service) values at the
data source (for example, at the NVG2053) so a server can decide the best
method of delivery, that is the least cost, fastest route and so on.
DiffServ
DiffServ is a class of service (CoS) model that marks packets so that they receive
specific per-hop treatment at DiffServ-compliant network devices along the route
based on the application types and traffic flow. Packets are marked with DiffServ
Code Points (DSCP) indicating the level of service desired. This allows the
intermediary DiffServ-compliant network devices to handle the packets differently
depending on the code points without the need to negotiate paths or remember
state information for every flow. In addition, applications do not have to request a
particular service or give advanced notice of where the traffic is going.
3
3. The NVG2053 does not support DiffServ at the time of writing.