Paessler PRTG

VoIP monitoring
software PRTG


  • icon check white 2
    QoS Monitoring & IP SLA Monitoring. All in one.

  • icon check white 2
    PRTG monitors the VoIP quality and runs VoIP latency tests
  • icon check white 2
    PRTG alerts you before
    phone errors occur







All-in-one VoIP monitor



prtg kv 1




 i How PRTG defines sensors

In PRTG, “sensors” are the basic monitoring elements. One sensor usually monitors one measured value in your network, e.g. the traffic of a switch port, the CPU load of a server, the free space of a disk drive. On average you need about 5-10 sensors per device or one sensor per switch port.

View video (3:26 min.)

Free QoS monitoring

Free QoS monitoring

The predefined PRTG QoS (Quality of Service) Round Trip Sensor measures the Quality of Service of your lines. Some of the parameters covered by this sensor are latencyjitterpacket loss, duplicate packets, and the Mean Opinion Score (MoS). This sensor is included free of charge!

Free IP SLA monitoring

Free IP SLA monitoring

Higher-priced Cisco switches and routers have a built-in monitoring tool, or so-called IP SLA monitoring. Among other things, IP SLA monitoring measures the quality of your service.

PRTG provides a preconfigured Cisco IP SLA Sensor for this purpose. With this sensor, PRTG lets you monitor your Cisco device data as part of the free trial version that you can use to get started. You may also choose to use it as part of your license, and thereby simplify the calculation of your purchase cost.

Customizeable notification system

Reduce workloads

The PRTG alarm feature runs discreetly in the background and focuses on that which is most important. Notifications are customizable according to your needs.

Decide when alerts should be sent, and the way you would like to receive them: by email, SMS, or push notification. As an IT manager, you can rest assured that you will be notified of issues promptly, before emergencies crop up. This alarm feature is likewise included!

Stabilize your network

Personalizeable dashboard

Thanks to the dashboard designer, you can create your own personal dashboard - and keep a constant eye on your entire monitoring environment. Even while on the go, you'll enjoy a constant overview by way of our app, which is available for Android and iOS.

Comprehensive network monitoring

Comprehensive network monitoring

PRTG is more than "just" a VoIP monitoring tool. It also lets you monitor, among other things, your bandwidthLANservers, and CPU. PRTG is an all-in-one solution. Once it is configured, your monitoring is good to go, and you can confidently go about your work. It is easy to see why so many of our customers love our tool!


Views of VoIP monitoring with PRTG


A quick overview of PRTG: VoIP monitoring definitions:

Voice over Internet Protocol (VoIP)

Voice over Internet Protocol (VoIP)

VoIP has become the telephony standard in companies and groups. Every VoIP call saves money. VoIP software is easier to configure and more versatile. The voice is digitized, then sent across the network connection and reassembled. This process, however, is prone to malfunctions. Some examples: packets arrive too late, as duplicates, or in the wrong order...




QoS Monitoring

QoS Monitoring

With QoS (Quality of Service) monitoring, data line performance is monitored using parameters such as latency, packet loss, and jitter. QoS monitoring can take place internally, i.e. as inside a large building (the company LAN). Otherwise, the connection to external offices in other locations can be monitored if the latter are equipped with remote probes suitable for VoIP monitoring.


IP SLA configuration

IP SLA configuration

For IP SLA monitoring, first you must properly configure your Cisco devices, and then add them to PRTG. Be sure to enable SNMP access, for data will be queried via this protocol. In the second step, create the appropriate Cisco IP SLA sensor and follow the subsequent instructions. The first data will arrive in no time at all. More information on IP SLA.



Your VoIP monitor – even on the go

PRTG is set up in a matter of minutes and can be used on a wide variety of mobile devices.


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

vendors vm ware


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



stephan linke

Practical tip: “Hey Stephan, do you have any tips for VoIP monitoring?”

“To simulate a telephone that uses the same network as your real IP telephone, simply set up our QoS Reflector Script on a Raspberry Pi and connect the latter to the desired point on the network. By doing so, you can guarantee that you are measuring the right network path with our QoS Round Trip Sensor. This is important because VoIP traffic is usually treated with priority.”

Stephan Linke, technical support at Paessler AG


PRTG makes your job easier

Our monitoring software frees you to focus on other tasks by promptly notifying you of potential issues.


time white

Save effort

PRTG gives you one central monitoring tool for your servers and entire network. Enjoy a quick overview of your whole infrastructure via our dashboard and app.

brain white

Save time

Getting started with PRTG is a breeze. Setting up or switching from another network monitoring tool is easy thanks to the auto-discovery and pre-configured device templates.

money white

Save money

80% of our customers report substantial cost savings with network monitoring. Your costs of licenses will likely pay for themselves within weeks.



Frustrated with your current monitoring software? A tip for those making the switch

Do you currently use Nagios or other commercial monitoring software? Frustrated with awkward user interfaces and hidden costs? Then make the quick and easy switch to PRTG. Our Smart Setup is extremely user-friendly. Configuration takes a few short minutes. Preconfigured sensors are automatically created during setup - another free PRTG feature. 


PRTG – Smart Setup

by Kimberley, Product Evangelist

Here we show you the first steps with PRTG: the initial configurations,
we explain how easy PRTG works and how the software is built.

View video (16:11 Min., English)


Measuring quality of service (QoS) with PRTG

When calling, perhaps the following are true: There is static on the line. There are delays. There are echoes.
If so, then you have a problem with the quality of your VoIP service. Take advantage of the parameters below to measure performance.



Latency measures the time data packets need to travel from the sender to the recipient. According to ITU-T, which is responsible for telecommunications standards within the International Telecommunications Union, delays should not exceed 125 milliseconds. When it comes to latency, PRTG recommends a maximum delay of 100 milliseconds, in order that you may be notified sufficiently in advance and can react before noticeable disruptions occur.

Packet losses

Packet loss is one of the most frequent errors to take place during VoIP, as well as during video conferences and streaming. ITU-T recommends a maximum loss rate of 5 percent. For packet losses, PRTG recommends a default setting of 0%. For even the smallest losses can cause interruptions. PRTG also lets you know if packets are "duplicates" or "out of order."  

Mean Opinion Score (MOS)

The MOS rates the call quality on a scale of 1 to 5. The higher the score, the better the quality. The rating is based on jitter, latency, and other parameters. MOS is a kind of summary that is displayed in the sensor overview with the other key information.


Jitter is also an important parameter for determining your quality of service. Jitter measures the deviation from the average latency value. PRTG recommends that this deviation be less than 20 to 25 milliseconds. This value, too, lies significantly below the ITU-T recommendation.


Included in VoIP monitor: preconfigured PRTG sensors

QoS (Quality of Service) Round Trip Sensor

The QoS (Quality of Service) Round Trip Sensor monitors the quality of the network connection while taking QoS parameters such as latency, packet loss, and jitter into consideration. Read more about the QoS (Quality of Service) Round Trip Sensor here.

QoS (Quality of Service) One Way Sensor

The QoS (Quality of Service) One Way Sensor monitors the quality of the network connection between two probes. Find out more about the QoS (Quality of Service) One Way Sensor here.

Cisco IP SLA Sensor

This sensor takes advantage of the ability of Cisco devices, which feature IP SLA, to read and analyze data. Find out more about the Cisco IP SLA Sensor here.

SNMP Cisco CBQoS Sensor

Even Cisco devices with CBQoS can be monitored with their own special sensor. Find out more about the SNMP Cisco CBQoS Sensor here.

SIP Options Ping Sensor

This sensor displays the SIP status code directly so the sysadmin immediately knows what is going on: SIP Options Ping Sensor.


VoIP disruptions – and how best to eliminate them



When you switch to Voice over Internet Protocol (VoIP), you’re bound to experience disruptions. Common disruptions are when one or both of the parties on the line are no longer audible. These disruptions can arise during the buildup to the call or during the call itself. Common error messages include 404 (remote switch not found) and 500 (server error). You can find a full list of error messages here.




Disruptions can be caused by many things. Users might be using their Internet phones incorrectly, errors may arise while configuring your gateway or QoS settings, or something may be wrong with your hardware. Another reason may be that your provider is not delivering the agreed upon bandwidth and is therefore in breach of your service contract (SLA). This can lead to increases in latency and lost data packets.




PRTG helps with the troubleshooting process. Errors are sniffed out much faster. Whether latency, packet loss, or other QoS issues: with PRTG, you’ll immediately see where the problem lies and can quickly go about resolving minor errors and disruptions. You can also improve the voice and overall quality of your calls. The same goes for video quality and streaming.


quote andreas reimann

“The support we received from Paessler AG was extremely reassuring. Their reaction time, know-how, and solutions were outstanding in every department.”

Andreas Reimann, Senior Networking Communication Architect at Zürich Airport. Zürich Airport uses more than 4,500 sensors for its monitoring


Trusted by 500,000 users and recognized
by industry analysts as a leader


“Fantastic network and infrastructure monitoring solution that is easy to deploy and easier still to use. Simply the best available.”

Read more reviews

“Software is absolutely perfect, Support is superior. Meets all needs and requirements, this is a must have solution if you are needing any form of monitoring.”

Read more reviews

“The tool excels at its primary focus of being a unified infrastructure management and network monitoring service.”

Read more reviews


3 common questions asked by companies with regard to VoIP

Why should we switch to VoIP?

Many companies seek to benefit from the advantages of VoIP solutions: IP telephony can be operated from any location in the world, which is also helpful when employees work from home. As language packs are transferred via the Internet, connection costs are significantly lower, especially when it comes to international calls. What’s more, in a few years’ time, old ISDN lines will be shut down completely.


What should we look for in a VoIP provider?

Various B2B providers offer cloud solutions for companies. Any decision should be based on the provider’s service, conditions, and performance. Other important considerations are availability and reliability - both should be at least 99%. Consult the provider’s data protection and data security policies. You’ll want to know, among other things, if the cloud provider operates its data centers in Europe.

Why is monitoring necessary?

In the event of disruptions and/or downtime, a VoIP monitor such as PRTG can help. Monitoring immediately lets you know when problems arise. You’ll therefore be able to take action before users know something is awry. As a result, you’ll free up a lot of your technical support department’s time.


Free VoIP monitoring vs. closed-source software

Packet delay

Free VoIP monitoring software

You can try the full, unlimited version of PRTG for 30 days free of charge. After this time, you’ll continue to get access to 100 sensors for as long as you like. If you’re only interested in keeping an eye on your VoIP, these 100 sensors will allow you to set up VoIP monitoring. The alarm, dashboard, and reports features are also available indefinitely in the free version of PRTG.



Packet loss

Closed-source VoIP monitoring tools

Some VoIP tools (including PRTG) offer licenses which enable you to set up extensive network monitoring. With a license, you can monitor your network devices, applications, services, and much more. Thanks to comprehensive overviews, you’ll immediately see if something is causing a problem in your network. In other words, you'll ensure your network runs trouble-free.




Also interesting:

Printer Monitoring: With PRTG you know the status of every printer. See detailed printer error messages at a glance and get informed if printer replacement is necessary.

Ping Monitoring: PRTG uses ping to check the availability of all your network devices. If the ping fails, you will be notified immediately.

SSL Monitoring: PRTG determines the extent to which your connections are protected. You can therefore learn if they are strong, weak, or not protected at all.


Create innovative solutions with Paessler’s IT partners

Partnering with innovative IT vendors, Paessler unleashes synergies to create
new and additional benefits for joined customers.


Integrating monitoring results from PRTG into NetBrain maps makes the foundation for network automation.

Read more


With ScriptRunner, Paessler integrates a powerful event automation platform into PRTG Network Monitor.

Read more


Combining their tools to a powerful solution for advanced analysis and automation, KnowledgeRiver and Paessler enable IT teams to ensure best performance for their infrastructure and networks.

Read more


“Easy to implement and configure with good technical support.”

R. v. S., ICT Manager at Heinen & Hopman Eng BV


PRTG the multi-tool

PRTG: The multi-tool for sysadmins

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

  • HTTP API: Access monitoring data and manipulate monitoring objects via HTTP requests
  • Custom sensors: Create your own PRTG sensors for customized monitoring
  • Custom notifications: Create your own notifications and send action triggers to external systems
  • REST Custom sensor: Monitor almost everything that provides data in XML or JSON format


Still not convinced?



More than 500,000 sysadmins love PRTG

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

Still not convinced?


Monitor your entire IT infrastructure

Bandwidth, servers, virtual environments, websites, VoIP services – PRTG keeps an eye on your entire network.



Try Paessler PRTG for free

Everyone has different monitoring needs. That’s why we let you try PRTG for free. Start now with your trial.




Network Monitoring Software - Version (September 20th, 2023)


Download for Windows and cloud-based version PRTG Hosted Monitor available


English, German, Spanish, French, Portuguese, Dutch, Russian, Japanese, and Simplified Chinese


Up to 100 sensors for free (Price List)

Unified Monitoring

Network devices, bandwidth, servers, applications, virtual environments, remote systems, IoT, and more

Supported Vendors & Applications

cisco logo grey 40 dell logo grey 40 hp logo grey 40 ibm grey40 netapp grey40 linux grey40 aws grey40 windows grey40 vmware grey40 citrix grey40 exchange grey40 apache grey40 oracle grey40