Maximizing Network Performance: Understanding MOS and Its Importance for IT Network Managers


IT network managers are under a lot of pressure to keep their networks operating at peak performance. Connectivity is the new oil, so businesses and other users have little tolerance for networks that crash, go slowly, or cause jitter, buffering, or lag during bandwidth-heavy activities like video conferencing. 

But as user expectations have risen, networks have become larger, heavier, and more difficult to manage. Today’s enterprise networks are far more complex and extensive than they were a few years ago, and often encompass both legacy networks and new cloud networks and multi-cloud environments. 

Network management teams rely on various metrics and measurements to keep on top of network performance and ensure that user experience is high, and one of these is Mean Opinion Score, or MOS.

What is MOS?

Despite the name, MOS is less to do with subjective human opinion, and instead relies on objective metrics around network performance. MOS is essentially a formula that evaluates and quantifies the quality of voice and video calls, based on a number of parameters. This makes it a useful metric for network managers to track how well a given network supports activities like VoIP calls and video conferencing. 

Originally, every MOS score was calculated by surveying expert observers, but today, most MOS scores are based on an objective measurement method that uses automated algorithms or metrics. Subjective ways to arrive at an MOS score are still in use, but for the purposes of this article, we’ll focus on objective, or metric-based, MOS. 

How to Measure MOS

To arrive at an MOS, network managers or IT teams convert individual values that measure different elements of network performance into a single score. MOS scores are typically between 1 and 5, with 1 signifying “bad” and 5 signifying “excellent”, although there are also other scales in use. 

An MOS of 1 would mean that the user can’t hear other people in a VoIP or video call, even if they’re in quiet surroundings, because the connection keeps cutting out or is too weak to support the call. An MOS of 5 means that you can easily hear and see everything on the connection, without any effort. 

Before you can calculate the MOS, you need to arrive at the R-Factor. The R-factor is derived from metrics such as packet loss rates, jitter, and latency, using a given recommendation from the International Telecommunications Union (ITU-T). R scores are usually between 50 (bad) and 90 (excellent). Although MOS has been standardized by the ITU-T, MOS scores still vary from one organization to the next, because they assess the R-factor in different ways. 

The Benefits of Objective MOS Measurement Techniques

Objective MOS measurement techniques bring a number of benefits, primarily an increase in efficiency and consistency. Because these techniques are automated, they deliver faster results, so networks can be evaluated more efficiently. Faster results make real-time monitoring a possibility, enabling continuous network quality assessment. 

Automated metrics use predefined algorithms or models, which reduce the variability that inevitably comes from human assessment. They also result in lower costs than subjective measurements, which require trained evaluators and controlled listening environments. 

The Challenges of Objective MOS Measurement Techniques

However, metric-based MOS brings challenges as well. Human perception of sound and video quality is influenced by many factors, and objective MOS techniques might not be able to accurately take them all into account. MOS measurement techniques are also not standardized. Different systems use different algorithms or metrics, which makes it challenging to aggregate scores and can hamper the reliability of MOS measurements across different platforms. 

At the same time, new coding schemes, formats, and transmission methods are emerging as technology advances. MOS measurements might struggle to keep up with these developments, and could require frequent updates and calibration to remain accurate and relevant.

The Importance of MOS for IT Network Managers

MOS is a valuable scale for IT network managers for a number of reasons, but primarily because it helps improve user experience and identify network issues more quickly. MOS is similar to quality of experience (QOE) scores, in that both are user-centric metrics that assess the quality of a user’s experience for a given service or technology. They use similar factors, including latency and packet loss, and contextual factors like network conditions and device capabilities. 

However, QOE is broader in scope, relating to more factors such as responsiveness, interactivity, visual quality, and ease of use, and is used in fields like streaming services, gaming and virtual reality. MOS is more narrowly focused on voice quality and is more often used in telecommunications. MOS has more stringent parameters than QOE, since voice and video call quality is more quickly affected by network issues than web browsing. 

Identifying Network Issues

MOS scores can be a valuable guide for network managers to identify potential problems and degradations in the network. If MOS scores drop below a certain threshold, it indicates that users are experiencing problems with the network. Network operators can measure MOS scores to monitor network performance over time. Sudden drops or sustained low MOS scores can alert operators to potential issues that require investigation and resolution.

Network management teams can also compare MOS scores between different segments or devices, to focus troubleshooting efforts in the right areas. 

How Network Managers Can Improve MOS

Given that MOS is a direct reflection of user experience, it’s worth it for network managers to invest time and energy into improving MOS scores. The main ways to improve MOS scores are through network optimization, and ongoing proactive network monitoring. 

Network Optimization

IT network managers are responsible for designing and optimizing network infrastructure to ensure efficient and reliable data transmission. They evaluate network capacity, bandwidth, latency, and packet loss to eliminate bottlenecks and improve overall network performance. By ensuring a robust and well-designed network, they can minimize disruptions and maintain high-quality communication.

Network managers also need to track and manage quality of service (QOS), which relates to traffic prioritization and traffic shaping. By allocating sufficient bandwidth and minimizing latency and packet loss for critical applications, they improve MOS and provide a better user experience.

IT network managers collaborate with service providers, such as internet service providers (ISPs) or telecom carriers, to ensure effective service delivery. By actively engaging with service providers and monitoring service level agreements (SLAs), they can maintain a high level of service quality and improve MOS.

Proactive Network Monitoring

As well as optimizing the network for positive MOS scores, network management teams need to continuously monitor networks to proactively maintain MOS levels. They employ network monitoring tools to track KPIs like latency, jitter, and packet loss, and respond quickly to any unexpected variations in these KPIs. 

Network managers also monitor bandwidth usage patterns, identify peak usage periods, and allocate resources accordingly to ensure that sufficient bandwidth is available to handle the network traffic effectively. Effective bandwidth management helps prevent congestion and maintain consistent quality for voice and video communications, leading to an improved MOS.

It’s important to implement the right monitoring tools and technologies for proactive network monitoring. NetOp, for example, offers AI-powered network monitoring and alerts that deliver early warnings about anomalies in the networks, and can often automate the response, increase bandwidth, and adjust resource allocation to resolve them more quickly. By proactively identifying and resolving network issues, network managers minimize disruptions and maintain optimal MOS.

Best MOS Practices for IT Network Managers

There are a number of things that IT network managers should put into place to ensure that MOS scores remain high. 

Establish a Baseline for MOS Scores

One important action is to establish baseline MOS scores which benchmark user experience. It’s valuable both to compare MOS scores against the network itself, and against benchmark figures from other similar networks. With a baseline, benchmarked MOS score, network management teams can proactively monitor network performance and user experience with more confidence and ease. 

Here’s a general guide to establishing a baseline MOS for network performance. 

  • Define the testing parameters to evaluate the audio quality. This could include bandwidth, latency, packet loss rate, and jitter.
  • Select your preferred standardized testing methodology that aligns with the technologies and protocols being used in your network, like ITU-T P.800 or P.862. 
  • Configure the test environment to represent the network conditions you want to evaluate. This may involve simulating different impairments like latency, packet loss, jitter, or network congestion. 
  • Prepare standardized audio samples that cover a range of audio characteristics, including speech clarity, background noise, and audio artifacts, to use as test media.
  • Repeat the process multiple times under different network conditions, to account for variations and ensure a more comprehensive understanding of network performance.
  • Document and validate the testing methodology, parameters, and results obtained during the testing process by comparing them with industry benchmarks or known acceptable quality levels for the specific network application.

Once you have established a baseline MOS, it serves as your reference point for evaluating the network’s performance over time. Monitor the network regularly and compare the new MOS scores with the baseline to identify any degradation or improvement in audio quality.

Implement MOS-driven Policies

By incorporating MOS as a KPI, network management policies prioritize the end user’s perspective, ensuring that service quality is aligned with user expectations. When SLAs include MOS as a KPI, it helps providers transparently measure and report compliance with the SLA. High MOS scores indicate superior service quality and enhance customer satisfaction, contributing to customer retention and loyalty.

By prioritizing MOS, service providers can enhance customer satisfaction, retain customers, and differentiate themselves in a highly competitive landscape.

Regularly measuring and tracking MOS scores also allows network operators to identify performance issues, diagnose root causes, and take appropriate actions. MOS can be instrumental in troubleshooting network issues and resolving customer complaints related to communication quality. When MOS scores drop below acceptable levels, network administrators can analyze network performance metrics, identify bottlenecks, and rectify the underlying problems to restore satisfactory service quality. 

MOS thresholds or targets enable network management policies that set specific quality goals and ensure that the network consistently meets or exceeds those standards. For example, incorporating MOS as a KPI helps network managers make informed decisions regarding network capacity planning and optimization. By correlating MOS scores with network utilization, administrators can identify potential capacity constraints and allocate resources effectively.

MOS Can Be Valuable for Network Management

By shining a light onto user experience, MOS scores offer a valuable way for IT network managers to ensure that networks are performing optimally and that user experience is high. Incorporating MOS as a KPI in network management policies and benchmarking and monitoring MOS scores provides a user-centric approach to assessing and improving service quality. It enables network administrators to monitor performance, troubleshoot issues, optimize resources, and deliver exceptional communication experiences to end users. 

By prioritizing MOS, service providers can enhance customer satisfaction, retain customers, and differentiate themselves in a highly competitive landscape.

Find out how NetOp can help you improve your MOS