Understanding Latency Testing

Nowadays there is a high standard expected regarding the quality of phone calls and the expereince they provide. However, there are many issues that can occur with a voice connection, one of the most common and frustrating being latency. Latency is the time delay from when you speak to when the other person hears your voice. Latency can be caused by a number of factors in the call path, including the number of network hops and the chain of hardware components that ultimately link the call.

To stay ahead of the competition, businesses depend on clear communication channels in their customer interactions, and more and more are taking a truly proactive approach to audio quality management. From examining the Spearline dataset, we’ve found that 1 in 25 calls fail to connect or suffer other critical customer-impacting failures.  

Latency test

How can a business be proactive through understanding the customer call flow and detect variations? Using the Spearline Latency Test you will be able to replicate your customer’s call flow and allows you to quantify the amount of latency your customers may be experiencing.  

So how does it work?
  1. The client sets up a number that, once dialled, is placed in ‘echo back’ mode (all audio received is immediately echoed back down the line)  
  2. Spearline in-country server dials your toll/toll-free number  
  3. Spearline server sends audio tones that, once received, are echoed back to the Spearline server  
  4. Spearline measure the round trip time of the audio tones (the time from when the audio was sent to when it was received)


By implementing the Spearline latency test you will be allowed to proactively measure any delay, and, with repeated testing, detect where there are variations over time. 


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How do you measure Latency?

Latency can be measured in one or both directions and is quantified in terms of milliseconds (ms). Latency is measured in two ways:  

  1. One-way latency is the time it takes for a data packet to travel in one direction only and it is generally used to diagnose network problems. 
  2. Two-way latency, also known as ‘round trip latency’, measures the round trip time and this figure is used to calculate MOS (mean opinion scores).  
What is measured?
  • Connection success or failure

  • Post dial delay (between the number being dialled and the call being answered)

  • Latency (or round trip time of audio)

Key benefits include:
  •  Identify and report issues before they significantly impact customers
  •  Identify high or variable latency that affects your customer’s experience
  •  Provides data that allows you to identify changes that have a positive effect on latency  


To find out more about our latency tests and how to set them up in your organization, please download our latency fact sheet.

For further information on how to test the latency levels that your organization is experiencing globally, download our latency whitepaper today.  

Sign me up!

If you are a Spearline customer and you are interested in adding Spearline latency tests to your platform, please speak to your dedicated customer engagement manager, email support@spearline.com or call +353 28 51460.  

About us

Spearline provides quality assurance tools for business communication services, allowing you to proactively manage your inbound and outbound voice, SMS and Fax services. Spearline is cloud based , which means no physical infrastructure is required at your end, and provides worldwide coverage with a presence in over 70 countries. For further information, or if you have any further questions please get in touch with us.


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