I read an article in “Light Reading” this morning that discusses how a survey revealed that more than a third of VoIP service providers rely on customer complaints to find out about voice quality. I’m not surprised. In fact, I’d bet that the number is even higher.
Whether you’re a service provider or responsible for your organization’s IP Telephony you should have the systems in place so that you understand with precision, and in real time, the quality of the service that you’re delivering to your clients. In my view, anything else is completely unacceptable.
Sadly, VoIP quality and troubleshooting tools are often not given the attention they deserve in the planning or budget stages of an IP Telephony implementation. Often, I’ve been told by clients “We have all of the network management tools we need”. In many instances, this is simply not the case. Traditional network management tools may not reveal issues that will cause serious voice quality issues for VoIP. Typically, these tools (properly implemented and monitored) will immediately detect Layer 1 or 2 issues but will often be completely oblivious to temporary congestion or other network conditions that cause unacceptable packet loss, delay or jitter which directly impact voice quality.
I will discuss this subject in depth in a future article. In the meantime, you may want to research the built-in management tools in your IP Telephony vendor’s solution and check out some of the following links:
http://www.brixnetworks.com/
http://www.netiq.com/
http://www.qovia.com/
http://www.empirix.com/
http://www.home.agilent.com/
By the way, Brix Networks offers this free tool to help you test your VoIP quality from your location to various places in the world. It’s a great way to prove to your VoIP service provider that your voice quality issues are not due to your network or, reveal that they are!
http://www.testyourvoip.com/
What follows is the results of a test from my home to Boston this morning. No wonder my voice quality sucks!
Test Details
The information below explains why your call quality score (MOS) was less than perfect.
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Media Quality
Signaling Quality
MOS Analysis From You TO Boston
Media Quality
MOS 2.9 / 5.0(Best with G.711 is 4.4)
Degradation Sources
Codec 0.57 26.9%
Latency 0.12 5.7%
Packet Discards 1.16 54.1%
Packet Loss 0.28 13.2%
Codec
G.711 (PCM at 64kbps, 20ms RTP payload, 80kbps IP BW)
Round-TripLatency 342 ms
Packet Discards 5.5%
Packet Loss 1.3%
Loss Periods
Min: 20 ms
Avg: 100 ms
Max: 420 ms
Burst Loss
Jitter
Min: 0 ms
Avg: 22 ms
Max: 660 ms
Signaling Quality
Post-Dial Delay 140 ms
Call Setup Time 156 ms
Media Delay 469 ms
MOS Analysis FROM Boston To You
Media Quality
MOS 4.2 / 5.0(Best with G.711 is 4.4)
Degradation Sources
Codec 0.58 73.9%
Latency 0.08 9.8%
Packet Discards 0.13 16.2%
Packet Loss 0.00 0.0%
Codec
G.711 (PCM at 64kbps, 20ms RTP payload, 80kbps IP BW)
Round-TripLatency 342 ms
Packet Discards 0.8%
Packet Loss 0.0%
Loss Periods
Min: 20 ms
Avg: 60 ms
Max: 100 ms
Burst Loss
Jitter
Min: 4 ms
Avg: 6 ms
Max: 183 ms
Signaling Quality
Post-Pickup Delay 303 ms
Call Setup Time 315 ms
Media Delay 335 ms
Rick McCharles
http://www.ric.ca/
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