An increasing number of businesses and individuals are using VoIP solutions instead of traditional telephone services. One popular use of VoIP is to make video calls. These are becoming increasingly common – for obvious reasons. They allow teams to ‘meet-up’ whilst reducing the need to travel to meetings. However, this technology is not entirely flawless with voice termination lag being just one potential issue.
The following are the most common causes of lagging when it comes to video calls, together with some steps can be taken in order to resolve the issues.
Latency
In terms of video, latency is defined as the length of time between a ‘frame’ being captured at one end and being displayed at the other end. Low latency is something that is desirable for any task that requires real-time interaction. The three most common types of delay are propagation delay, handling delay, and queuing delay.
Propagation delay is the delay caused because the speed at which electrons can travel through copper or fibre (approx. 125,000 miles per second) is slower than the speed of light (186,000 miles per second). On its own, this delay is not usually noticeable but if it is part of several delaying factors, it could be.
Handling delays are caused by devices that forward the ‘frame’ through the network. Slow networks exaggerate these delays and they are more of an issue in VoIP than in traditional telephone networks/systems.
Queuing delays occur when the number of data packets that are being sent out exceed the number that the outbound interface is able to handle in a given amount of time. To deal with this, they are held in a queue resulting in queuing delay.
One key way to tackle latency is to prioritise VoIP traffic over the network. There are numerous techniques for doing this, including bandwidth reservation, policy-based network management, class of service, type of service, and multi-protocol label switching.
Jitter
Jitter is the measure of the variability of the latency across a network over a certain period of time. This is one of the most common problems when it comes to VoIP call/video quality problems. Because the information (voice and image) is divided into packets, each piece of data travels via a different path from the receiver to the sender. If these packets arrive at their endpoint in a different order than that in which they were sent, the video call quality will suffer. An excellent solution for this is to use jitter buffers. These buffers temporarily store the arriving data packets in an attempt to minimise delay variations in latency. Any packets that are deemed ‘too late’ to arrive are discarded.
In managing and configuring a network to optimise voice traffic and minimise jitter, many firms turn to VoIP specialists such as IDT. These firms offer a range of solutions, together with expert advice in managing and configuring VoIP-based services. As a global leader in voice termination services. IDT’s unique, self-serve portal gives customers the power to manage IPs, purchase DIDs, process payments and access a range of other services.
Buffering
Video data buffering occurs whenever processing is required to wait until a specific volume of data is free. Buffering can vary from just a few pixels right through to a number of frames. The dominant contributor to this latency tends to be the Decoder Stream Buffer (DSB).
The best way to solve this issue is to ensure that you have the best video encoder for your particular system. The best encoders allow you to control the bit rate and the averaging period and offer features such as content-adaptive rate control, rate control granularity and sub-frame rate control.
Poor/unreliable Internet connection
The majority of ISPs are configured for surfing the web rather than VoIP usage. The best thing to do here is to use the premium internet services that the major cable and DSL high-speed internet providers offer specifically for businesses.
Router
Without a good enough router (and one that is correctly configured for packet prioritisation), video call quality can be negatively impacted when other users on your network attempt to execute tasks that require high bandwidth use (e.g. downloading a large file). Because many small businesses use their internet connection for data and voice, this is one of the most common causes of video call quality issues.
Investing in a VoIP router that gives priority to VoIP packets on your network will help with video call quality. These routers are not overly expensive.
Incorrect internal network configuration
In companies where both voice and data are routed over the same network, it is important to correctly configure the network to deal with VoIP traffic. Without this configuration, video call quality is likely to suffer. Again, the best way to deal with this is to use a high-quality VoIP capable router.
