Everyone has dealt with some quality issues on calls. You connect and suddenly it sounds as if you're underwater or on an airfield. If you video conference a lot, you've probably seen other issues like combing, pixelation, or ghosting. Sometimes it can be pretty funny, but if you were on an important conference call, these kinds of issues could negatively affect the outcome.


For example, if one of your fellow employees was on a conference call that could make or break your organization, poor VoIP or video quality could negatively affect the outcome, especially if it was difficult to understand the other participants. Additionally, poor call quality negatively affects everyone who uses the VoIP network. Consistently not being able to understand what's happening on a call is frustrating and can reduce the desire to communicate via that vector.


What is QoS?


QoS stands for Quality of Service and refers to metrics that directly correlate to how well your network performs. In this context we're talking about the quality of your network and its translation to VoIP or video. QoS takes into account several factors such as packet loss, latency, jitter, and MOS.


Packet Loss

Packet Loss is a measure of information loss over your network connection. An example of packet loss is when words are garbled or missing from a conversation. Though packet loss is inevitable in any network, the goal is to identify where packets are lost in transmission so you can act to minimize information loss and maintain high QoS for your services.



In VoIP, latency is the difference in time between when one caller speaks and when the other caller hears what the first has said. An extreme example of latency is during calls to the space station. The long pause after someone asks a question is not the astronauts gathering their thoughts; it's a combination of waiting to hear the question, gathering their thoughts, and then waiting for their response to reach Earth. Excessive network latency can cause noticeable gaps and synchronization issues, particularly when VoIP is used with other types of data, as in a videoconference.



Jitter is a measure of the variation in network latency that results in a loss of synchronization over time. In VoIP phone calls, users experience jitter as distracting noise, clicks, and pops.



MOS, or Mean Opinion Score, is an industry standard measure of call quality expressed on a scale from 1 to 5, where 1 is extremely poor call quality and 5 is excellent call quality. MOS is primarily a user input, but some VoIP monitor can calculate MOS based on other algorithms. Most IT shops do not want their MOS to go below 3.5.


What do Monitors Do for Me?


Well, if you install a QoS monitor, like SolarWinds VoIP and Network Quality Manager, you can tell where the trouble is in the network when issues arise and begin to either troubleshoot the issue or begin to make plans to modify or expand your network before disaster strikes. You could make recommendations to ameliorate the network congestion based on what you know about the network and improve your QoS. Most QoS monitors come with alerts, so you can closely monitor your latency, packet loss, or jitter.