Can You Hear Me Now? Identifying VoIP Call Quality Problems (IT Toolbox Blogs)



Many businesses switch seamlessly from landlines to Voice over Internet Protocol (VoIP), but you may find that your employees are experiencing some call quality problems after you’ve swapped services. Before you call your VoIP provider for troubleshooting experience, try to identify exactly what type of call problems your business is having. By knowing how to describe your call quality problems, you’ll get better service from your VoIP service, even if you can’t replicate the problem on every call.

Identifying Common VoIP Call Quality Problems

There are three main Quality of Service (QoS) problems with VoIP: echoes, choppiness and delays. Echoes make your calls sound like you’re speaking in a vast cavern and can make it almost impossible to carry on a conversation. Choppiness occurs when words or bits of words are dropped completely. People often refer to choppiness as the call “breaking up.” Delays are easy to spot because there are noticeable pauses when different people speak. When you experience problems with your VoIP, you can have several underlying issues that snowball into severe problems with call quality.

Roots of VoIP Delays

 

Some VoIP delay is inevitable because it takes time for sound to travel. However, total end-to-end delay must be less than 150 milliseconds (ms) to achieve good voice quality. Longer VoIP delays that are noticeable to the human ear are often caused by queuing or handling delays. When VoIP services discuss delays, they often use the term “latency.” Latency is the lag time between the pieces of information delivery and is measured in milliseconds. To ensure acceptable QoS, queuing delays should be less than 10 ms. Handling delays can be addressed by adjusting the Digital Signal Processor (DSP) if your company’s bandwidth is sufficient.

VoIP Echo Causes

If you have frequent reports of problems with echoes, have your employees check their phones before trying other troubleshooting. Sometimes an echo is the result of acoustic feedback and is resolved by turning down the volume of the handset to reduce crosstalk. If acoustic feedback isn’t the cause of the echo, you may have to troubleshoot your line echo canceler. Otherwise, VoIP end-to-end delays could be the underlying cause of any echoes.

Explanations for VoIP Choppiness

Call choppiness is often caused by a combination of jitter and packet loss. In simple terms, jitter is variation in delays between when each packet of audio data is delivered. Small amounts of jitter are unavoidable, but are addressed with a jitter buffer.

Packet loss refers to delays when bits of data are lost completely, which causes the lost sounds to be omitted from the audio. Often, packet loss occurs when the network is too busy, and it intentionally drops some packets to address abnormal delays. Other causes of packet loss include link failure, buffer overflows and misrouted packets. You can address small amounts of packet loss through the playback codec, which can disguise the loss of these small bits of information. Sometimes excess buffering to reduce delays can cause packet loss.

VoIP call problems can negatively impact customer service and worker productivity, so it’s important to address these concerns promptly. In most cases, your VoIP service provider will be able to use a variety of tools to diagnose and correct any audio problem. There are also a variety of troubleshooting tools that can help you determine the root cause of the problem.

Source: SANS ISC SecNewsFeed @ May 31, 2016 at 05:09PM

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