The Beginner’s Guide to Voice Quality Testing

The Beginner’s Guide to Voice Quality Testing

An introduction to Voice Quality Testing 

We’ve all experienced a phone call where the voice quality makes it almost impossible to hold a conversation. ‘Sorry, what was that?’, ‘Can you repeat that?’… Poor voice quality can lead to misunderstandings, stress and, sometimes, calls being abandoned completely.

Poor voice quality affecting your personal calls is frustrating. If your business relies on those voice calls though, just sitting back is not an option. But how do you even know what level of voice quality people calling your phone numbers experience? If your business is global, your customers’ experience may vary considerably, depending on where they’re calling from, and which contact number they’re calling. The only way to know for sure what callers are experiencing is by testing voice call quality on your network. So, what is voice quality testing? Here’s an introduction… 

How do you conduct a voice call quality test?

Voice quality testing could be as simple as asking someone to make a call to one of your contact numbers, and rate various aspects of the quality of the call. In fact, this is what many contact centers, conferencing services and phone number providers have resorted to in the past, enlisting the help of anyone from freelancers to employees, friends and family. But this method isn’t exactly scientific or reliable. A person’s experience of voice quality can be subjective, they won’t be able to provide an accurate measurement of all characteristics, and they won’t necessarily be available at all times to conduct test calls. Relying on a process like this to test voice call quality across a large number of global contact numbers would also be unmanageable and costly.

A more scientific method of testing voice call quality is to use a pre-recorded voice sample. The test compares the audio output (at the phone line’s ‘listener’ end), to the original voice file (played on the ‘talker’ side), to create a fully unbiased and objective indicator that tests the actual voice quality the listener experiences. 

A brief outline of how Spearline tests voice call quality:

  • An in-country server, connected to standard phone lines – either landline or mobile – with ISDN signaling, dials your contact number. 
  • The server sends a DTMF tone which your IVR is configured to recognise (eg ‘9-8-7-5-7’)
  • Your IVR connects the test call to a pre-loaded audio (WAV) file. This plays a voice sample back over the line, which is recorded on the Spearline server and analyzed to generate an audio quality score.  
 

By originating test calls from an in-country server, voice quality testing done in this way can uncover the true experience of callers from different parts of the world, while having full control to conduct test calls at any time, day or night.

What can voice quality testing tell you?

Using the type of voice quality testing outlined above, the call recording can be analyzed and compared with the original voice sample using an objective, recognised voice quality measure called PESQ (Perceptual Evaluation of Speech Quality). PESQ is an ITU (International Telecommunication Union) standard for measuring audio quality, taking into consideration characteristics such as:

  • Audio sharpness
  • Call volume
  • Background noise
  • Variable latency or lag in audio
  • Clipping
  • Audio interference
 

This allows you to test voice call quality on any type of call – mobile or fixed-lines; toll and toll-free services, VoIP or PSTN – using an agreed international standard. 

With regular voice quality testing like this, you have data you can trust on the precise voice quality your customers are experiencing at any given time, and how this varies when calling from different locations.

How can voice call quality testing help your business?

We’ve covered how to test voice call quality, but what can you do with this information once you have it? In other words, what’s the point of voice quality testing? 

1. Help your engineers get ahead of voice quality issues 

Proactive voice quality testing means being alerted to issues at the earliest possible moment. Although your engineering team will be monitoring the performance of your internal network, they have no control and, often, no visibility of what’s happening outside of that. So, the reality is that information on voice call issues – be they calls not connecting, poor voice quality, or other quality issues – is often left to trickle through to the engineering team via customer service. This means that the fault can be ‘live’ for a long time before it’s even raised.

Frequent proactive voice quality testing is a way to ensure you receive early warning where issues are occurring, and the intelligence to fix issues before they become a problem. Voice quality testing conducted by Spearline, for example, comes with full call detail records that allow you to pinpoint issues, investigate more quickly and reduce your mean time to resolution (MTTR). 

2. Protect your brand

The ultimate aim of this early warning on voice quality problems, of course, is to protect your brand. A degradation of voice quality can only lead to a degradation in customer experience, which, in turn, causes damage to your brand’s reputation. Being on top of voice quality issues as they happen, with the intelligence to be able to make adjustments to voice call routes ‘on the fly’, means you are able to proactively manage this aspect of your brand’s reputation.

 3. Test voice call quality being provided by your telco/carrier

Businesses rely on their telecommunications carrier to provide an agreed level of service. And, indeed, telcos rely on their partners to pass a voice call along the full call path. That path for a customer making an international call may have a variety of potential routes that it could follow, with hops and handovers made to carrier partners along the way.

Yet, despite contracts and service level agreements (SLAs), businesses are blind to their carriers’ true performance, and carriers are blind to their partners’ performance. Some may be transcoding (compressing audio files) at busy times to save on data. This may not mean that calls are being dropped completely, but it will result in a loss of voice quality. And, because this may only be happening at particular times, it can be even more difficult to spot.

With proactive voice quality testing, you’ll be able to spot straight away if this is happening. If you have a large network, with multiple potential routes for your voice calls, you’ll be able to test all those routes, thus ranking the performance of your providers. Armed with this intelligence, you’ll be able to make informed choices on the telcos and routes you use, as well as holding your carrier to account if they’re not performing to SLAs.

 New to Spearline?

Spearline provides quality assurance tools for business communication services, allowing you to proactively manage your inbound and outbound voice, SMS and fax services. Our latest WebRTC products offer testing, monitoring and support for web-based communications.

We work globally across business sectors, supporting contact centers, conferencing services, and more to successfully connect with their customers and employees. For further information, or if you have any further questions please get in touch.  

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