Chapter 13 Voice Over IP (VoIP)
Page 13- 32 UNIVERGE NEAX 2000 IPS Request for Proposal (RFP) Reference Guide
Issue 6
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. Filler Time
Codec 10 msec 20 msec 30 msec 40 msec
G.711 (64 Kbps) 32 Kbps 16 Kbps 10.67 Kbps 8 Kbps
G.729a (8 Kbps) 32 Kbps 16 Kbps 10.67 Kbps 8 Kbps
G.723.1 (6.3 Kbps) N/A N/A 10.67 Kbps N/A
G.723.1 (5.3 Kbps) N/A N/A 10.67 Kbps N/A
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).
Total Bandwidth per transmit stream
Codec 10 msec 20 msec 30 msec 40 msec
G.711 (64 Kbps) 96 Kbps 80 Kbps 74.67 Kbps 72 Kbps
G.729a (8 Kbps) 40 Kbps 24 Kbps 18.67 Kbps 16 Kbps
G.723.1 (6.3 Kbps) N/A N/A 16.97 Kbps N/A
G.723.1 (5.3 Kbps) N/A N/A 15.97 Kbps N/A
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.
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Bandwidth in
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Time (not to scale)