NEC UNIVERGE NEAX 2000 IPS Reference Manual page 274

Chapter 13 Voice Over IP (VoIP)
Bandwidth utilization
The following chart shows the amount of bandwidth for IP overhead per the fill times set in the
PBX system. The higher the fill time used, better performance from the PBX and IP network
can be realized due to the smaller number, yet larger (in size) packets generated.
Codec
G.711 (64 Kbps)
G.729a (8 Kbps)
G.723.1 (6.3 Kbps)
G.723.1 (5.3 Kbps)
This chart shows the total amount of bandwidth in layer 3 per voice call during the transmit
stream from an IP trunk or IP station. The value shown is based on the fill time from the table
above and the bandwidth required by the encoding/decoding algorithm that is used (codec).
Codec
G.711 (64 Kbps)
G.729a (8 Kbps)
G.723.1 (6.3 Kbps)
G.723.1 (5.3 Kbps)
This chart shows bandwidth usage (G.729A) based on an idle state followed by a keep alive
message with a call setup and voice usage next. Time is not to scale.
Keep Alive
Bandwidth in
Kbps
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10 msec
32 Kbps
32 Kbps
N/A
N/A
Total Bandwidth per transmit stream
10 msec
96 Kbps
40 Kbps
N/A
N/A
Bandwidth per Process
Call Setup
16
14
12
10
8
6
4
2
0
Time (not to scale)
Filler Time
20 msec 30 msec
16 Kbps 10.67 Kbps
16 Kbps 10.67 Kbps
N/A 10.67 Kbps
N/A 10.67 Kbps
20 msec 30 msec
80 Kbps 74.67 Kbps
24 Kbps 18.67 Kbps
N/A 16.97 Kbps
N/A 15.97 Kbps
Voice Usage
Call
Teardown
UNIVERGE 2000 IPS Request for Proposal (RFP) Reference Guide
NEAX
40 msec
8 Kbps
8 Kbps
N/A
N/A
40 msec
72 Kbps
16 Kbps
N/A
N/A
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