nexVortex BLOG

SIP Trunking:
Voice Quality and Why It Matters

Patti Dean

Are you delivering quality to your customers?

“And what is good, Phaedrus, and what is not good — need we ask anyone to tell us these things?”

– Socrates.

Whether it be through a weak mobile phone connection or a poor quality Internet call, we’ve all experienced the frustration of missed syllables, missed vowels, or missed emotional subtleties caused by poor voice quality. You may have gotten used to it but no one has to tell you that you are experiencing a poor quality call – you know it immediately.

But familiarity is the enemy of objectivity.  Just because we may have become used to a relatively poor quality call, doesn’t mean we have to settle for it.  Various methods determine voice quality such as Mean Opinion Scores (MOS) and there are some key causes of poor voice quality.  If your calls aren’t clear, your company probably is not sounding its best.


What are some causes of poor voice quality?

No QoS – In very simple terms, Quality of Service (QoS) refers to the capability of a network to provide better service quality to a selected type of network traffic over another (different) type of traffic. For example, treating real-time voice traffic more stringently than the delivery of an email message.  QoS can vary greatly depending on how your service provider is handling the voice traffic transiting to and from your business premise.


Using the wrong codec. “Codec” is short for “coder-decoder” – in this case, it converts sound vibrations, such as your voice, into ones and zeros, and then decodes them back to “ear friendly” sounds. Your VoIP solution should support a codec which provides, at a minimum, the same quality as a landline. G.711 is an example of a codec which provides good quality voice.


Insufficient bandwidth. The available internet bandwidth needs to be taken into account when one considers Voice over IP sound quality. A regular phone line uses 64 Kbps for an uncompressed voice call.  G.711 is a narrowband audio codec that provides toll-quality audio at 64 Kbps.  A G.711 codec uses about 87.2 Kbps of bandwidth for each call (signaling not included).  The 87.2 Kbps of bandwidth assumes the use of Ethernet for transport which adds some additional overhead.

The calculation to get to 87.2 Kbps typically only considers the Ethernet frame size in the calculated number.   If one goes further and considers the total Ethernet packet size (including things like preamble and inter-packet gap among others), this number can be even slightly higher.

For sake of simplicity, we will use the 87.2 Kbps in our example.  If you have a small office with 10 people and 6 of them are on their phones simultaneously, voice calls alone will take up at least 6 X 87.2 Kbps = 523.2 kbps.  This doesn’t  take into account data usage (like email or file transfers, or web surfing) which could be occurring on the same internet connection.

So be sure you have enough bandwidth to support your voice AND data needs.


Latency, packet loss, and jitter. When one considers the path that voice over IP packets take from their origination point to their destination point, it is easy to imagine a number of things which could go wrong. Some packets are delayed getting from point A to point B (latency); some get lost or thrown away when the network gets congested or when a packet gets corrupted (loss) and still others arrive faster or slower than other packets in the same stream causing variability in delay (jitter). All these phenomena can have a negative impact on voice quality.

We will take a deeper look at each of these in a future post but the ability to determine them, or control them, has a significant impact on the ability to deliver voice quality.


Should you know your voice quality?

You can order a dessert, smell it, and look at it all you want, but you won’t know how good it is until you actually taste it – the first reason you should be aware of voice quality is so you know you’re getting a top-notch product. Even more importantly, knowing the quality of your calls is kind of like taking a look in the mirror before stepping into a meeting – it is how your company presents itself.

If words are jittered, or there is an echo, it not only hinders general communication, but subtleties of inflection and emphasis can be missed, and your brand can be hurt.  Don’t let that happen to you.


Voice quality matters

Obviously, how you come across to your clients is just as important as ensuring you don’t miss a single phone call.  nexVortex’s company goal is to provide you with a refreshingly uncommon experience, from crystal clear connectivity, to exceeding your customer service expectations. We offer a wide range of options and services, allowing us to customize a plan perfectly suited to meet your voice communication needs. If you’re ready to get the most out of every call, connect with our friendly staff today!


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