One of the key benefits of moving to a unified communications (UC) framework is the ability to swap out old, limited PBX-based systems for the flexibility and added functionality of a VoIP system. It is important, though, when choosing a service provider for a UC solution, to make sure they are able to accommodate the Quality of Service (QoS) needs of the business and deal adequately with issues such as jitter, packet loss, and latency.
QoS is an umbrella term for a number of protocols and technologies designed to guarantee the quality of data flow over a network. Generally this involves prioritizing certain types of network traffic over others to ensure that network services such as VoIP, which are susceptible to latency, aren’t adversely affected.
Latency is the delay between when a data packet is sent and when it is received. It’s basically the time it takes for data to get from one point on the network to another. It is affected by a number of factors, including conversion from one data type to another, physical distance between the two points, the number of hops or redirects along the route, and encryption. This has some pretty obvious implications for VoIP traffic, particularly in light of its real-time requirements. Round trip latency of more than 250ms is noticeable to users, and the IUT recommends never exceeding 300ms.
Packet loss occurs when a router receives more data than it can pass through at one time. This can be a frequent occurrence with VoIP traffic simply because of the volume of data generated by real-time voice communication. The effects of packet loss on a VoIP call are usually noticed as stuttering sound, a “tinny” metallic quality to the other person’s voice, or outright dropped calls. Packet loss of more than 1% is usually considered unacceptable. High latency levels tend to exacerbate packet loss.
Jitter is a variation of latency where the timing of packet arrival at the destination is inconsistent. This doesn’t affect most types of internet traffic very much – it’s unnoticeable when loading a web page, for example – but can seriously affect VoIP calls. Generally, jitter results in delays in the conversation, similar to a “buffering” effect. Unless excessive it doesn’t hamper communication as much as the other issues discussed here, but it can be frustrating for users.
By giving VoIP traffic a higher priority level through QoS protocols such as Class of Service and Type of Service, issues such as latency and jitter are kept to a reasonable level. Policy-based network management and bandwidth reservation also help. A good cloud services provider will be able to provide the right combination of these strategies to ensure the necessary QoS.