NEC UNIVERGE SV9100 Manual page 9

Example two:
CODEC: G.729
Frame Size: 80ms
Voice Frames per Packet: 8
Voice Sample Size: 80ms (frame size x Voice Frames) Bandwidth Required: 12Kbps
Note: Figures above do not take into account Layer 2 overhead. This varies dependant on the Layer 2
protocol used (e.g. Ethernet, Frame Relay, PPP).
The graph below shows the bandwidth requirements for 1 VoIP call using the CODECs and Networks
specified. This can be used for an indication of the required bandwidth.
2.6.1 Bandwidth Graph
?
Increasing the bandwidth on a data connection can resolve some voice quality issues, however this
is often impossible due to physical cable limitations, or more commonly, cost.
2.7 Frames per packet?
See explanation in the
Increasing the amount of frames per packet (also described as VIF, Sample Size, and Fill Time) can
reduced the bandwidth requirement and therefore improve voice quality. If the number of frames per
packet increases too much the voice quality can deteriorate as the voice calls become more
susceptible to packet loss and additional delay is introduced.
Bandwidth section above.
Part 1: VoIP Reference Manual 9