NEC 2000 IPS manual Bandwidth utilization, Codec Filler Time Msec

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		Filler Time
	10 msec	20 msec	30 msec
G.711 (64 Kbps)	32 Kbps	16 Kbps	10.67 Kbps
G.729a (8 Kbps)	32 Kbps	16 Kbps	10.67 Kbps
G.723.1 (6.3 Kbps)	N/A	N/A	10.67 Kbps
G.723.1 (5.3 Kbps)	N/A	N/A	10.67 Kbps

40msec

8 Kbps

8 Kbps

N/A

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).

Codec	Total Bandwidth per transmit stream
	10 msec	20 msec	30 msec
G.711 (64 Kbps)	96 Kbps	80 Kbps	74.67 Kbps
G.729a (8 Kbps)	40 Kbps	24 Kbps	18.67 Kbps
G.723.1 (6.3 Kbps)	N/A	N/A	16.97 Kbps
G.723.1 (5.3 Kbps)	N/A	N/A	15.97 Kbps

40msec

72 Kbps

16 Kbps

N/A

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.

		Bandwidth per Process
	16	Call Setup						Voice Usage
Keep Alive
	14
	12									Call
Bandwidth in	10
	8									Teardown
Kbps	6
	4
	2
	0
	1	4	7	10	13	16	19	22	25	S1
										28
			Time (not to scale)

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