Nortel BCM50 Configuration Manual page 124

124 Chapter 9 Configuring telephony resources
Table 23 H323 Media parameters record (Sheet 2 of 2)
Field Value
Settings
Enable Voice <check box>
Activity Detection
Jitter buffer Auto
None
Small
Medium
Large
G.729 payload size 10, 20, 30, 40, 50, 60
(ms)
Default: 30
G.723 payload size 30
(ms)
G.711 payload size 10, 20, 30, 40, 50, 60
(ms)
Default: 30
Incremental payload <check box>
size
Enable T.38 fax <check box>
Force G.711 for 3.1k <check box>
Audio
NN40020-603 NN40020-603
Description
The voice activity detection, also known as silence suppression
identifies periods of silence in a conversation, and stops sending
IP speech packets during those periods. In a typical telephone
conversation, most of the conversation is half-duplex, meaning
that one person is speaking while the other is listening. For more
information refer to "Silence suppression" on page
If voice activity detection is enabled, no voice packets are sent
from the listener end. This greatly reduces bandwidth
requirements.
G.723.1 and G.729 support voice activity detection.
G.711 does not support voice activity detection.
Performance note: Voice activity detection on all networked
BCMs and IPT systems (VAD setting on IPT systems) must be
consistent to ensure that interacting features such as Transfer
and Conference work correctly. As well, the Payload size on the
IPT must be set to 30ms.
Default: Disabled
Select the size of jitter buffer you want to allow for your system.
Default: Auto
Set the maximum required payload size, per codec, for the VoIP
calls sent over H.323 trunks.
Note: Payload size can also be set for Nortel IP telephones. See
the BCM 4.0 Telephony Device Installation Guide (N0027269).
When enabled, the system advertises a variable payload size
(40, 30, 20, 10 ms)
Enabled: The system supports T.38 fax over IP.
Disabled: The system does not support T.38 fax over IP
Caution: Operations note: Fax tones that broadcast through a
telephone speaker may disrupt calls at other telephones using
VoIP trunks in the vicinity of the fax machine. Here are some
suggestions to minimize the possibility of your VoIP calls being
dropped because of fax tone interference:
Locate fax machine away from other telephones.
Turn the speaker volume on the fax machine to the lowest level,
or off, if that option is available.
When enabled, the system forces the VoIP trunk to use the
G.711 codec for 3.1k audio signals such as modem or TTY
machines.
Note: This setting can also be used for fax machines if T.38 fax is
not enabled on the trunk.
529.