IP SLA monitoring with PRTG:
Keep the line open!

  • PRTG monitors the quality of your VoIP-connections
  • PRTG comes with special sensors for Cisco IP SLA monitoring
  • PRTG monitors quality of service without expensive hardware

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

IP SLA monitoring:
Optimize the quality of service of VoIP and your network



Lost connections and poor sound quality
 during video conferences and customer calls are extremely annoying. Frequently, calls have been planned well in advance and are unable to be rescheduled on short notice. For the smooth functioning of voice over IP and video streaming, a stable flow of data packets is a must. With IP SLA monitoring, you’ll ensure a high quality of service. And by preventing malfunctions and verifying service level agreements, you’ll save time and money.

PRTG monitors quality of service (QoS) in real time regardless of your hardware, and comes with special sensors at no extra cost. Expensive Cisco IOS routers are required for Cisco IP SLA monitoring which monitors a network’s various VoIP parameters. Even if you do not have IP SLA-compatible routers or switches, you can still keep an eye on the network quality between two random network nodes by using Paessler’s QoS sensors. To do so, all you need are two regular Windows computers. As a result, you’ll ensure the quality of your network connections without having to shell out exorbitant amounts for IP SLA-compatible hardware.

With PRTG, everyone will work with peace of mind.

An introduction to IP SLA monitoring with PRTG

Data collected


iWhat is a sensor?

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.)

The PRTG Network Monitor comes with a Cisco IP SLA sensor that monitors the following parameters:

  • ICPIF (Calculated Planning Impairment Factor): Predefined combinations of packet loss and packet delay for VoIP
  • MOS (Mean Opinion Score): Calculation of the subjectively perceived connection quality based on parameters such as jitter and packet loss
  • Packets which arrive in the wrong order
  • Packets which arrive too late
  • Average VoIP Jitter value (a kind of packet delay)
  • Average round-trip time (network latency time)
  • Transaction RTT
  • Packet loss

While QoS sensors and the IP SLA Sensor query similar data, QoS sensors also calculate MOS. With the IP SLA Sensor, this value is read directly by the Cisco device.

“The greatest advantage of PRTG? You get to rest easy.“

Steffen Ille, Bauhaus-University of Weimar, Germany

How IP SLA monitoring with PRTG works

VoIP connections are susceptible to even the most minor of problems. At the same time, it is extremely important that they comply with service level agreements (SLAs). If data packets do not arrive on time, get lost, or become mixed up, then the quality of the connection will drop dramatically. For optimal quality of service, jitter and packet delay variation (PDV) values should be as low as possible; packet losses, duplicate packets, and packets arriving in the wrong order must be avoided at all costs. The PRTG Network Monitor is a VoIP monitoring software that uses a variety of sensors for QoS monitoring and for the presentation of these values: the QoS Sensor (one-way and round-trip), the SNMP Cisco CBQoS Sensor, and the IP SLA Sensor.

IP SLA Sensor: Cisco devices with the IP SLA feature gather various information about VoIP-related parameters, such as response time, latency time, jitter, packet loss, and packet delay. The most interesting values for VoIP are the mean opinion score (MOS) and ICPIF. The PRTG IP SLA Sensor monitors all these results. PRTG can be used as IP SLA monitoring software without extra add-ons or costs. In addition, the SNMP Cisco CBQoS Sensor lets you use Class-Based QoS when monitoring Cisco devices.

QoS sensors: When monitoring quality of service, PRTG deploys QoS sensors which verify the quality of a network connection between two end points. VoIP jitter, packet loss, packet delay, and other relevant values are measured. QoS sensors provide similar values to those gathered by IP SLA monitoring but are not limited to monitoring Cisco routers which include the IP SLA feature. PRTG is not just a LAN monitor: by using “remote probes,” you can even monitor quality of service via VPNs, WIFI and WAN connections.

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trust our software. Every day.

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  • 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

Configuring IP SLA monitoring



When configuring the PRTG IP SLA monitoring, you’ll need to add the IP SLA-compatible Cisco device you wish to monitor to PRTG by indicating its network address. Be sure to enter the SNMP access data correctly, for PRTG uses SNMP to query the corresponding IP SLA data of target devices.

Next, create a new sensor on this device to represent your Cisco router or switch in PRTG: on the device, click on “Add Sensor” and enter “IP SLA” in the search field. Then add the “Cisco IP SLA” sensor, and on the following screen select the parameters you wish to monitor.

Within minutes, the current values will appear on your PRTG dashboard - Your IP SLA monitoring is up and running.


 VoIP connection quality at a glance
 – even 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!


7 good reasons to choose PRTG as your IP SLA monitoring tool

Successful video conferences instead of lost connections

Successful video conferences instead of lost connections

VoIP monitoring lets you optimize the stability and sound quality of video conferences. Save yourself the embarrassment of lost connections and horrible sound quality.

Custom notifications

Custom notifications

Should parameters fall below or exceed your self-defined threshold values, PRTG will inform you immediately by email, SMS, or push notification – wherever you happen to be.

Automation for a lighter workload

Automation for a lighter workload

It’s impossible to monitor the quality of all VoIP connections manually. With PRTG, you can sit back and relax knowing sensors are doing the work for you – and that you’ll be notified automatically if a problem arises.

Connection and bandwidth consumption optimization

Connection and bandwidth consumption optimization

PRTG will show you how applications and services use bandwidth, which in turn will enable you to develop specific solutions for all your business needs.

Verification of service level agreements

Verification of service level agreements

By monitoring VoIP and verifying quality of service, IT services will become an aspect of your company which employees can count on in their day-to-day work.

Special IP SLA sensors at no extra charge

Special IP SLA sensors at no extra charge

Paessler charges no extra costs for the monitoring of IP SLA-compatible hardware. IP SLA is simply incorporated as another sensor type, and can therefore even be used as freeware.

Compatibility with all hardware

Compatibility with all hardware

With QoS sensors, the quality of service of VoIP connections can be monitored even in the absence of Cisco devices.

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

PRTG simplifies your day!

Let our IP SLA monitoring software run in the background. So you can concentrate on your day-to-day tasks with peace of mind.

PRTG saves time

With PRTG, you get one centralized IP SLA monitoring tool for all your hardware. You’ll enjoy a quick and complete overview at all times via our dashboard and app.

PRTG saves worry

Round-the-clock monitoring of the quality of service of your VoIP connections has never been easier. The built-in alarm feature of PRTG is quick to respond, before the system fails or employees complain.

PRTG saves money

80% of our customers report substantial or even exceptional cost savings in the area of syslog monitoring. The experience of our customers shows that the costs for licenses have paid for themselves in an average of a few weeks.


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PRTG as network discovery tool

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Log monitoring with PRTG

Network utilities

PRTG supports a variety of protocols like SNMP, NetFlow, IPFIX or packet sniffing

PRTG: The swiss army knife for sys admins

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
  • New REST API Sensor: Monitor almost everything that provides XML or JSON

Award winning solution

We work hard on making our software as powerful and easy-to-use
as possible for our customers each and every day.
Of course it makes us proud when we get awards for that.



German quality

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


Made in Germany: The PRTG Network Monitoring Tool is the fruit of an engaged team. The company was founded by Dirk Paessler. The Paessler AG headquarters are located in the city of Nuremberg, in the heart of Germany. We combine typical German virtues such as high quality standards, industriousness, and commitment with international, cosmopolitan flair. Read more about our firm here. By the way: We are regularly looking for new recruits.

Case Studies: Airports, utility companies, banks, colleges, hospitals: PRTG is present in every industry. For each of our customers, business and organizational processes depend on the proper functioning of the network infrastructure. The PRTG customer satisfaction is close to 100%. Read in our case studies how our customers use PRTG.

Product tests: It goes without saying that we are convinced by the quality of PRTG. But what about the others? PRTG has always performed extremely well in tests. PRTG user “LanLine” sums it up best: “PRTG was already good several years ago, and has gotten better from version to version ever since.” Such has been our steadfast and sincere goal. Read more about monitoring software product tests and comparisons here.

Support: Our support team works hard every day to help customers solve their monitoring problems. Our goal is to resolve all inquiries within 24 hours (on business days). We've drafted a comprehensive manual and built up an extensive knowledge base featuring videos, webinars, and FAQs. All support, of course, is also included!

Getting started is easy: The trial version is free, which means you can try our monitoring tool risk-free. To switch to another version of PRTG, simply search for an appropriate license. You can upgrade any time you like.



Network Monitoring Software - Version (September 10th, 2019)


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