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 ability of network to access number of maximum bandwidth and deal with other network elements like error rate, uptime and latency which effects the performance. There are several meaning of Quality in networking,in simple way we can say that Quality is some thing in which speak 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

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

For voice service provider it is important to use quality of services in their network for VoIP traffic. There are number of factor which can effect the quality of VoIP traffic. Some of these i discussed below.


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


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

Packet Loss

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