Nortel VoIP Gateway, Configuration Manual, Page: 171 / 220

Silence compression on Full Duplex Links 171
Norstar VoIP Gateway Configuration Guide
When silence compression is enabled, voice packets are only sent when a speaker is talking. When
a voice is being transmitted, it uses the full rate transmission rate. Since the sender and receiver do
not share the same channel, the peak bandwidth requirement per channel is still equal to the full
transmission rate. The following figure shows the peak bandwidth requirements for one call on a
full-duplex link with silence compression enabled. The spare bandwidth made available by silence
compression is used for lower priority data applications that can tolerate increased delay and jitter.
Figure 52 One call on a full duplex link with silence compression
Time ->
Ba
nd
w
idt
h -
>
Bandwidth Used
Rx
Tx
Fred Here.
Hello Fred. This is Susan. Do you have a minute?
Time ->
Sure! Hi!
Ba
nd
w
idt
h -
>
Tx
Chan
Rx
Chan
Independent Tx and Rx bandwidth not shared by “half-
duplex” call. Bandwidth available for data apps.
Channel Max
Channel Max
Hello Fred. This is Susan.
Do you have a minute?
Fred here. Hi!
Sure!
Conversation
Bandwidth used
Independent Tx and Rx bandwidth not shared by half-duplex calls.
Bandwidth available for data apps.
Time
Channel/Link max
Tx
c
h
a
n
n
e
l
B
a
ndw
id
th
Tx
Rx
Channel/Link max
Rx
c
h
a
n
n
e
l
Ba
nd
wi
dt
h
Time