Jitter, packet loss, and latency can negatively affect the performance of Voice-over-IP (VoIP) calls. Check out this slide deck to learn more about monitoring your network performance to assure excellent VoIP call quality.

1. Panos Vouzis
panos@netbeez.net
@pvouzis

2. ● How long it takes for a voice packet to go from source to destination
(includes encoding time)
Internet3 2 1 3 2 1
15 ms

3. ● Variation in the delay of received packets
Internet3 2 1 3 2 1
25 ms
15 ms

4. ● Dropped packets = voice gaps
3 2 1 3 1
Packet loss: 33%

5. ● User score of voice call 1-5
I give it 4
I give it 4.5
MOS: (4+4.5)/2 = 4.25

6. MOS Quality Impairment
5 Excellent Very Satisfied
4 Good Satisfied
3 Fair Some users dissatisfied
2 Poor Many users dissatisfied
1 Bad Nearly all users dissatisfied

7. EffectiveLatency = AverageLatency + Jitter * 2 + 10
if (EffectiveLatency < 160)
R = 93.2 - (EffectiveLatency / 40)
else
R = 93.2 - (EffectiveLatency - 120) / 10
R = R - PacketLoss * 2.5
MOS = 1 + (0.035) * R + (0.000007) * R * (R-60) * (100-R)
https://netbeez.net/blog/impact-of-packet-loss-jitter-and-latency-on-voip

8. Packet Loss vs. Jitter vs. Latency
Latency
Jitter

9. Packet Loss vs. Jitter vs. Latency
Latency
Jitter