150 ITG engineering guidelines
QoS level
Network
delay (ms) Packet
loss (%) G.711
20 G.729A/AB
30 G.723.1 (6.3 Kbps)
30
199 1 fair poor good
199 2 fair poor fair
199 4 poor not recommended not recommended
199 8 not recommended not recommended not recommended
200 – 249 0 poor not recommended not recommended
249 1 poor not recommended not recommended
249 2 poor not recommended not recommended
249 4 not recommended not recommended not recommended
249 8 not recommended not recommended not recommended
250 – 299 0 poor not recommended not recommended
299 1 poor not recommended not recommended
299 2 poor not recommended not recommended
299 4 not recommended not recommended not recommended
299 8 not recommended not recommended not recommended
The QoS levels are equivalent to the following MOS values: See "E-Model" (page
73) for more details.
excellent 4.5
good 4
fair 3
poor 2
not recommended less than 2
Sample scenarios
Scenario 1 A local LAN has the following characteristics:
G.711 codec
20 msec network delay
0.5% packet loss
Tocalculate R = 94 - lc - ld - lp, use Table 29 "Impairment factors of codecs"
(page 148),Table30 "Impairment factors due to network delay" (page 148),
and Table31 "Impairment factors due to packet loss" (page 148):
G.711 codec: lc = 0
20 msec network delay: ld = 0
Nortel Communication Server 1000
IP TrunkFundamentals
NN43001-563 02.01 Standard
Release 5.5 21December 2007
Copyright© 2007, Nor tel Networks
.