How Quality of Service can affect In VoIP Calls

  • Fri, 08/14/2015 - 01:36 by aatif
What is Quality of Service

Quality of Service (QoS) is defined as the ability of the network to access a number of maximum bandwidth and deal with other network elements like error rate, uptime, and latency which affects the performance. There are several meaning of Quality in networking, in a simple way we can say that Quality is something in which to speak a clear voice, listen clearly without any noise. Service in VoIP means services which offered communication facilities to their consumer.

Factors Which Affect Quality of Service In VoIP Call

At the start quality of VoIP was not good. It is the big Hallmark of VoIP quality. But with the passage of time, there has been seen a lot of improvement in the voice quality of VoIP calls. Still, many people prefer traditional analog communication over VoIP. VoIP is mostly used in IP networks. It carries different types of traffic like video and voice traffic, carrying data. Some time network resources are congested it becomes the cause of low-quality VoIP calls.

For voice service providers it is important to use the quality of services in their network for VoIP traffic. There is a number of factors that can affect the quality of VoIP traffic. Some of these I discussed below.


We know delay as the process of VoIP traffic which reached from one endpoint to another endpoint. It is also called end-to-end delay. We can measure the delay in two ways. We can measure it one way or we can measure it through the round trip. The acceptable one-way delay voice is 150ms according to ITU G.114.A delay that is greater than 150ms causes poor voice quality and a bad effect on user experience.


Jitter is a variation in delay from one endpoint to another endpoint over time. Jitter causes the voice to degrade if it varies too widely in VoIP communication. VoIP network usually delivers the VoIP traffic at a constant rate by buffering at the endpoints. If jitter is too high its becomes difficult to buffer control it at endpoints finally the result is poor voice quality.

Packet Loss

Packet loss can be defined as a number of dropped packets in the data path during carrying the VoIP traffic from one endpoint to another endpoint. Usually, it is considered that three percent is a bearable limit for good voice quality. If this limit is increased from 1.5% it causes poor voice quality.