VoIP Quality Metrics You Should Know

Cloud Phone System
When building a stable and reliable technical solution, you’re only as good as your weakest link. It’s a short and sweet concept but it can be harder than it sounds at times. This is especially true with hosted VoIP and there’s a simple theory we’ve learned over the years. The devil is in the details. Your weakest link will almost certainly be different than someone else’s and planning ahead is a crucial step in your hosted VoIP deployment.

We’re kicking off a new blog series covering best practices for deploying Hosted VoIP in your business and our first topic is getting to know the VoIP quality metrics.

Many businesses get ready for their VoIP deployment by focusing on a single WAN metric: bandwidth. While very important, bandwidth only tells part of the story and ignoring the other metrics could jeopardize your entire project.

VoIP Quality Metrics

Bandwidth: Internet bandwidth describes the throughput capacity of your WAN connection. The numbers (usually measured in Mb/second) correlate to your download and upload speeds. But having a lot of capacity doesn’t always mean fast throughput.

Latency: This is the second part of the equation which measures how “fast” your link to another party is. Lower latency is always better. Cellular and satellite ISPs are notorious for having terrible latency which degrades the quality of your calls.

Jitter: In plain terms, the timing gaps between data packets being sent out on internet lines. Bad jitter is higher in millisecond count, with low or nonexistent jitter being best. Best effort connections such as DSL or DOCSIS (coax) have better jitter metrics than cellular or satellite services on average but a fiber connection is preferred for the absolute best results.

Packet Loss: Ever lose mail you’ve sent out in the postal system? That’s the real world equivalent of packet loss. A good connection should have zero packet loss. Even just a few percent of packet loss equates to terrible VoIP calls.

These metrics, along with compression and the codec used, are taken into consideration to determine your Mean Opinion Score (MOS).

What is a Mean Opinion Score?

A Mean Opinion Score (MOS) is a numerical measure to quantify the subjective nature of voice quality as registered by the human ear. MOS has been used for decades as a way to assess call quality and the most commonly used rating scale for MOS is the Absolute Category Ranking (ACR) scale, which ranges from 1 to 5. The levels of the Absolute Category Ranking are:

5 – Excellent
4 – Good
3 – Fair
2 – Poor
1 – Bad

 
An MOS of 4.3 and above is preferred for VoIP calls and when the MOS decreases to 3.5 or below, most users find voice quality to be unacceptable.

If your MOS scores are low or if you have issues with poor VoIP service, it’s time to improve the quality of your calls before you start losing business.

If you are considering Hosted VoIP for your business, let us know and our engineers will calculate your MOS and provide a free evaluation of your network.

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One Comment
  1. Thanks for the quality-metrics. Using these valuable list of the best practices when implementing or troubleshooting VoIP. Keeping these steps in mind will help to get the most from any VoIP network or VoIP service provider. Understand and measure call quality components. There are a variety of metrics you can use to assess VoIP call quality and best are mentioned here.

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