Jan 02, 2013

What's the most important factor in VoIP call quality?

Ok, I understand that I need a certain amount of bandwidth to ensure good call quality on a VoIP system, but what is the most important factor in call quality, assuming you have sufficient bandwidth? We have QoS rules in place that prioritize voice traffic, but how much do factors like latency and jitter affect sound quality?


It doesn't take all that much bandwidth for VoIP calls, and more often than not, I have found the problem lies elsewhere when there are call quality issues. Basically, once you have allocated sufficient bandwidth for each call, you should look at jitter, latency and packet loss. Excessive jitter creates problems with echo cancelers and can cause echoes and talk over. Latency can cause momentary silence during calls, which often results in people talking over each other (then pausing, then talking over each other again, ad infinitum). Excessive packet loss will cause voice to be distorted and/or sound "choppy". 

Here's an articles with some answers.

5 Curable Causes of Poor VoIP Call Quality

"If you are using a VoIP phone system, there is a good chance you have experienced poor call quality. This article discusses the causes of VoIP call quality problems and what you can do to correct them.

The causes of poor quality VoIP calls are easy to diagnose and correct. Your VoIP Service Provider should be able to identify and work with you to correct these problems. More importantly, these problems should not be ongoing. If your VoIP Service Provider is unable to correct your call quality problems, you need to find a different provider."
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