The Voice over Internet Protocol (VoIP) is a diverse group of technologies used to allow people to talk over the Internet in real-time. Although there is no unified protocol to implement these technologies, they have similar limitations and factors that affect their quality of service (QoS). QoS refers to the network performance of VoIP applications, as it affects end users, as well as a feature of routers that identifies and prioritizes traffic within their network (Yihunie & Abdelfattah, 2018). Two particular factors that can have a critical negative impact on the QoS of VoIP are packet delay and jitter. Delay, or latency, is the amount of time a packet takes to travel between its source and destination, while jitter is the variation in delay over time (Voip-info.org, n. d.). As these issues are practically unavoidable over a network, VoIP implementations generally have measures built in to compensate for them. However, these measures may be insufficient, causing deterioration of quality for the user, such as a loss of synchronization between speakers, or artifact noises that make it more difficult to listen to the received audio.
Delay and jitter are often caused by a generally poor network connection quality. Due to the nature of VoIP, timely reception and processing of packets is a critical factor for the application’s audio quality. Particularly in congested networks, delays can be caused by processing on the router as lower-priority packets are sent to their destination before VoIP ones. Modern routers have built-in prioritization features that automatically identify high-priority and time-sensitive packets, including ones sent by VoIP applications, and forward them ahead of others. Similarly, to compensate for jitter, they can buffer incoming packets and send them out at regular intervals, interpolating for ones that were not received or discarded due to exceeding the buffer’s size (Cisco, 2006). However, poor network quality, excessive processing delay, or other factors can still produce packet delay and jitter that routers are incapable of compensating for.
References
Cisco (2006). Understanding jitter in packet voice networks (Cisco IOS platforms). Web.
Voip-info.org (n. d.). QoS. Web.
Yihunie, F., & Abdelfattah, E. Simulation and analysis of quality of service (QoS) of voice over ip (VoIP) through local area networks. 2018 9th IEEE annual ubiquitous computing, electronics & mobile communication conference (UEMCON). Web.