How do you monitor and measure audio quality in IP PBX calls using tools like MOS or R-Factor?

1 What are MOS and R-Factor?

MOS and R-Factor are two common metrics that evaluate the audio quality of IP PBX calls. MOS stands for Mean Opinion Score, and it is a subjective rating of the voice quality on a scale from 1 (bad) to 5 (excellent). R-Factor stands for Rating Factor, and it is an objective measure of the voice quality based on several factors such as delay, jitter, packet loss, and codec. R-Factor ranges from 0 (poor) to 100 (best).

2 How to collect MOS and R-Factor data?

To collect MOS and R-Factor data, you need to use tools that can capture and analyze the voice packets that are transmitted and received by your IP PBX system. These tools can be software-based or hardware-based, and they can be deployed at different points of your network, such as the endpoints, the switches, the routers, or the servers. Some examples of these tools are Wireshark, PRTG, SolarWinds, or Cisco IP SLA.

3 How to interpret MOS and R-Factor data?

Once you have collected the MOS and R-Factor data, you need to interpret them to understand the audio quality of your IP PBX calls. Generally, a MOS score of 4 or higher and an R-Factor score of 80 or higher indicate good audio quality. However, these scores may vary depending on the type and configuration of the codec that is used to compress and decompress the voice signals. For example, a G.711 codec can achieve a MOS score of 4.1 and an R-Factor score of 93, while a G.729 codec can achieve a MOS score of 3.9 and an R-Factor score of 80.

4 How to troubleshoot audio quality issues?

If you find that the MOS and R-Factor scores of your IP PBX calls are below the acceptable thresholds, you need to troubleshoot the audio quality issues and identify the root causes. Some common causes of poor audio quality are network congestion, bandwidth limitations, misconfigured QoS settings, faulty hardware, or malicious attacks. To troubleshoot these issues, you can use tools that can perform tests, diagnostics, or simulations on your network, such as Ping, Traceroute, iPerf, or SIPp.

5 How to improve audio quality?

After troubleshooting the audio quality issues, you need to implement solutions that can improve the audio quality of your IP PBX calls. Some possible solutions are upgrading your network equipment, increasing your bandwidth, optimizing your QoS settings, choosing the right codec, or enhancing your security measures. You can also use tools that can monitor and optimize the audio quality in real-time, such as VQmon, NetEQ, or ClearOne.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?