This article applies to PRTG Network Monitor 12 or later, as well as to previous (deprecated) versions

VoIP Monitoring With PRTG

When it comes to Voice-over-IP communication, an astonishing sound quality can be archieved by using the latest high density (HD) audio codecs. So much for theory! In practical experience, VoIP communication isn't so easy. Users often experience connection failures, speech delays or a "robot-sounding" voice, echoes and lost speech fragments in Voice-over-IP telephony. Often, persistently annoying speech quality is the consequence.

The reason for this, generally spoken, is a bad Quality-of-Service (QoS) in the network, either on the sender's and/or on the receiver's side or somewhere in between. Among other failures and delays in your network, bad QoS can make VoIP communication virtually impossible. With PRTG Network Monitor, you are able to find the bottle-necks - even using the Freeware Edition!

Cisco's more pricey switches have a built-in QoS measuring feature called "IP-SLA" which can - among others - monitor the QoS between two Cisco switches. You can use PRTG to monitor the resulting measurements, as is also possible with other competitive monitoring solutions. But PRTG goes far beyond this.

With our own QoS sensors, you can monitor the network quality between any nodes you like (not only between routers). Introducing PRTG, you can monitor the QoS of any network structure without having to buy expensive IP-SLA capable hardware (although this is, of course, also possible). In this way, PRTG can help you improve the quality of your VoIP communication.

Overview: The Advantages of PRTG in Monitoring Quality-of-Service (QoS)

• No add-ons, plug-ins or specific infrastructure is necessary. Everything you need is included in PRTG.
• No special hardware necessary with PRTG. Other monitoring products that provide QoS monitoring only offer IP-SLA, which requires expensive Cisco hardware.
• PRTG can monitor IP-SLA, plus it measures the quality of a connection itself. In fact, our QoS sensors basically perform the same measurements as the IP-SLA feature does.
• PRTG can monitor Cisco CBQoS (Class Based Quality of Service) as of PRTG v13.x.5.
• PRTG can monitor the connectivity of a Session Initiation Protocol (SIP) server. SIP is a very common protocol in VoIP. You can monitor VoIP services this way by using PRTG's SIP Options Ping Sensor. It sends "auth" and "options" requests to the server and shows the response time.
• Using PRTG, you can monitor QoS
  • even in low profile networks that run in part or fully on cheap, unmanaged switches, and
  • across VPNs and WAN connections that the user may not have control over.
• When measuring QoS, with PRTG you are not limited to measuring connections between expensive Cisco boxes (which are mostly located "close to the core" anyway), so you may not even see the connection problems which are more likely on network edges, where often cheaper hardware is used.
• With PRTG, you can also measure the QoS in the "corners" of the network or remote locations. All you need is a PC running Windows, install a probe and then you can measure the data line quality.
• Even the Freeware Edition includes both the IP-SLA and QoS sensor!
• PRTG is likely the cheapest commercial enterprise grade software available for IP-SLA and QoS monitoring.

See Also

• PRTG Manual: QoS (Quality of Service) One Way Sensor
• PRTG Manual: QoS (Quality of Service) Round Trip Sensor
• PRTG Manual: Cisco IP SLA Sensor
• PRTG Manual: SNMP Cisco CBQoS Sensor
• PRTG Manual: SIP Options Ping Sensor