Mean Opinion Score: Monitor
your network’s MOS with PRTG


  • Monitor your Mean Opinion Score (MOS)

  • Monitor jitter, packet loss, and latency

  • QoS monitoring for VoIP

  • Alarm and reports included

  • 100 free sensors


Free Download

Unlimited version of PRTG for 30 days. After 30 days, PRTG reverts to a free version.
Or, you can upgrade to a paid license anytime.






What is the Mean Opinion Score?


The Mean Opinion Score rates the voice and image quality of a VoIP transmission. It is the arithmetical average of several parameters. The Mean Opinion Score is abbreviated as "MOS.” The lowest MOS is 1, while the highest MOS is 5. A score of 1 means that despite great effort, it is impossible to understand what is being said during the call (the call repeatedly cuts in and out). A score of 5 means the quality is excellent, with no effort required to understand what is being said. The MOS makes it possible to compare a variety of codecs and audio connections. 


Calculating the Mean Opinion Score with PRTG


PRTG comes with a number of sensors that monitor the quality of service (QoS) of your network. These sensors include the QoS (Quality of Service) Round Trip Sensor and the Cisco IP SLA Sensor. Among other things, these sensors display the Mean Opinion Score. As a result, you can keep a constant eye on the performance of your VoIP.

More on QoS and VoIP sensors

By the way: PRTG also monitors your Cisco hardware – at no additional charge.


MOS and other key values:
A sneak peek at your monitoring environment


5 common questions regarding
the Mean Opinion Score (MOS)

How is the Mean Opinion Score calculated?

Cisco devices calculate the MOS, while the PRTG IP SLA Sensor reads it. PRTG uses the QoS (Quality of Service) Round Trip Sensor to calculate the Mean Opinion Score. To do so, it must first obtain an R-value. Visit our knowledge base for more detailed information on how PRTG calculates the MOS.

What is a codec?

“Codec” is short for “coder-decoder.” With a codec, data or a signal is digitally coded then decoded. This process is not immune to dips in quality. In telephone networks, a large number of codecs are used, each of which has its own MOS. The MOS makes it easy to compare the quality of the various codecs. 

What is a typical Mean Opinion Score?

The Mean Opinion Score rates the quality of a voice transmission on a scale from 1 to 5. 1 is "bad,” 2 is “poor,” 3 is “fair,” 4 is “good,” and 5 is “excellent.” PRTG displays the MOS in the sensor which has been created for a particular device. You can choose to be notified whenever the score drops.

How does a test determine the Mean Opinion Score?

Several tests are used to determine the MOS. These tests take various quality parameters into consideration. The tests for voice transmissions have been defined by the ITU-T. We let you try the full version of PRTG for 30 days. Once the trial is over, you can continue to use 100 free sensors for as long as you please. If you’re looking for a quick and easy way to test your MOS, then PRTG will do the trick.

Which tools will monitor my Mean Opinion Score?

PRTG is network monitoring software that keeps a constant eye on your MOS. A quick glance at the dashboard suffices for determining if your company’s VoIP or video transmissions are experiencing difficulties. What’s more, PRTG notifies you promptly so you can quickly get down to troubleshooting. With PRTG, you’ll increase the stability of your network and give your IT helpline a much-needed break.


A quick glimpse into MOS values


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Free Download

Unlimited version of PRTG for 30 days. After 30 days, PRTG reverts to a free version.
Or, you can upgrade to a paid license anytime.



More than just MOS:
3 reasons why PRTG is the monitoring tool for you

MOS included

MOS included

PRTG comes with sensors for all your devices – even Cisco devices. There are no hidden fees. 100 sensors are free and never expire. If you need more, simply choose an appropriate license. Start small – you can always upgrade later. On average, you’ll need around 10 sensors per device for in-depth network monitoring.

Comprehensive monitoring

Comprehensive monitoring

There’s no doubt about it – stable VoIP calls are a must. But when calls start to cut out or drop, the error can lie in many different places. With PRTG, you no longer have to search for the needle in the haystack. Hardware, applications, bandwidth – you’ll immediately know when a device malfunctions. And the source of the error will be visible at a glance. You can even monitor the availability of your cloud applications.

Stable network

Stable network

PRTG works – quickly and without interruption. As a result, your network will be much more stable. Enjoy fewer support calls, less stress, and more time for other projects. PRTG often pays for itself in a few short months. That’s why more than 500,000 sysadmins worldwide put their trust in us.


Keep a constant eye on your network
– even while on the go

PRTG can be started within minutes and it's compatible with many mobile devices.


PRTG comes with all the features you need, plus more your IT infrastructure won't want to live without.


PRTG monitors these vendors and applications, and more, in one view!



Free Download

Unlimited version of PRTG for 30 days. After 30 days, PRTG reverts to a free version.
Or, you can upgrade to a paid license anytime.



Other key parameters (besides the MOS)



Jitter is the deviation between the delay in data transmissions. If this delay changes, then disruptions can occur during the transmission of data packets.

More on jitter monitoring

Packet loss

Packet loss

If data packets get lost, are duplicated, or arrive in the wrong order, then you can expect a significant drop in the quality of the transmission. Learn more about dealing with packet loss in your network.




Latency is the amount of time a packet needs to be sent to its recipient and then back to its sender. With each delay, image and voice quality suffer. Learn more about monitoring latency.



Practical tip: “Hey Konstantin, what can I do with the PRTG QoS Reflector?”

“When using our QoS (Quality of Service) Round Trip Sensor, you usually need to place a remote probe on a second Windows computer to measure the round-trip values of data packets. With the PRTG QoS Reflector, this is no longer necessary. The Reflector is a Python script that sends data packets from the endpoint back to PRTG. The QoS Reflector also runs on all Linux systems, even a small Raspberry Pi.”

Konstantin Wolff, Software Developer at Paessler AG


Over 95% of our customers recommend PRTG


Paessler AG worldwide trialled PRTG in over 600 IT departments.
The aim was to tune the network monitoring software closer to the needs of the administrators.
The result of the survey: over 95% of the participants would recommend PRTG - or already had.

Recommend PRTG


Learning the basics of network monitoring – 3 examples


Network mapping

Use the built-in PRTG Map Editor to quickly and conveniently drop & drag all your IT components into easy-to-read network maps. With the Sunburst View, you'll immediately see if everything is in order in your network – or if something looks fishy. More on network mapping with PRTG

Network diagnosis

Have you been asked to diagnose your network? We'll show you how to use PRTG as a diagnosis tool and get to the root of problems faster – all the while taking the software’s limitations into consideration. More on network diagnosis with PRTG

File monitoring

PRTG monitors individual files and notifies you if these files are modified. You can also use our tool to monitor log files, syslogs, and event logs. More on file monitoring with PRTG


PRTG is worth it: You’ll optimize your entire IT!

The costs for a one-year PRTG license usually pay for themselves within a few weeks.


PRTG improves the reliability of your network

PRTG improves the reliability of your network

PRTG saves
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PRTG saves network management costs

PRTG saves time
spent on network management



PRTG The Swiss Army knife

PRTG: The Swiss Army knife for sysadmins

Adapt PRTG individually and dynamically to your needs relying on a strong API:

  • HTTP API: Access monitoring data and manipulate monitoring objects using HTTP requests
  • Custom Sensors: Create your own sensors for customized monitoring
  • Custom Notifications: Create your own notifications to send alarms to external systems
  • REST Custom Sensor: Monitor almost everything that provides XML or JSON


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PRTG is used by companies of all sizes. Sysadmins love PRTG because it makes their job a whole lot easier.

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Network Monitoring Software - Version (December 1st, 2021)


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