QoS vs QoE - A “Model” Approach to Internet Telephony QoS-Quality of Service

QoS vs QoE - A “Model” Approach to Internet Telephony QoS-Quality of Service

By Evan Kirstel November 21, 2016 Leave a Comment
QoS vs QoE - A “Model” Approach to Internet Telephony QoS-Quality of Service by Evan Kirstel

QoS - Quality of Service (analytics) and QoE - Quality of Experience (user satisfaction) are tightly intertwined in an ever challenging and complex environment of networks, devices, mobile and applications. Bandwidth is often considered the cause for jitter, round trip delays, echo, crosstalk and noisy calls. As a technical professional and integrator, you are faced with planning in advance what the problems will be and providing instant solutions when the C-level calls to complain. The key issue is having tools that when the CXO calls complaining about having a terrible call with a customer you need a better answer than, "I don’t have any idea." Paessler has a technical tool designed to help you measure and manage your SIP network effectively and efficiently. As they say, “with this new QoS Round Trip sensor you can be sure that your network is in good shape and ready for VoIP, Skype, YouTube, video conferencing, and much more. It ensures deeper scrutiny of the network connection between two locations within one network segment, especially as regards packet loss.”

QoS - Quality of Service – “As is”

Telephone company lines are engineered for high quality and have been for more than 100 years. The internet has been and likely will always be “as is” because it was really designed for email not voice which as you know if it or other data gets delayed by minutes or more, you will never know. That is, if your data gets delayed it's ok but if voice/video gets delayed by even 100 milliseconds (sub seconds) it will jitter, jumble, garble, or worse. This is something humans don’t like and generally complain about. Adding more bandwidth does not automatically cure voice problems but it can help at an additional expense.

SIP or Session Initiation Protocol means placing your voice calls over your existing Internet data bandwidth. The SIP trunking providers push their lower costs because they don’t include the extra bandwidth you will need, thinking you already have too much. This is really important because you may likely not have enough data bandwidth for all your voice calls. Since voice is two-way the key metric is not only download but more importantly reliable upload speed. Most internet bandwidth access is asymmetrical meaning very high download speed and very slow upload speed. That is, you may think you have enough download speed for voice and data but not enough reliable upload speed for your voice calls and more importantly reliable QoS. Check your speed at speedtest.net or other service/app bandwidth and then again throughout the day to see what bandwidth speed you have in both up/down directions.

In the past, configuring this type of QoS plan required a great deal of network knowledge and device specific training using a command line interface or a rudimentary GUI. Experience with technologies, protocols or terms such as DiffServ (Differentiated Services), CoS (Class of Service), 801.1p, and ToS (Type of Service) were required for properly implementing a QoS solution. In addition, a traffic shaping router needed to be configured for classes and buckets, priorities, policies and speeds. Moreover, classifying VoIP traffic presents additional complexity as the RTP (Real Time Protocol) traffic, which carries the media, runs on typically on UDP ports that are often negotiated on the fly within the SIP/SDP signaling. Adding in in tools such as Paessler.com Network Monitoring‎ can give you insights as QoS problems may be and ways to fix the problem.


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