How to Perform Phone Number Testing


International toll and toll-free phone number testing is crucial to protect one of your key customer contact channels. Businesses today rely on multiple contact channels to give customers options, and to provide a level of self-service. 

Why should you consider phone number testing?

According to Call Center Helper, telephone contact remains the dominant channel, responsible for 63.6% of interactions.

The modern customer expects that the telephone number they dialed will work. Hence, it should work the first time and every time they call. Additionally, the call quality should be first class. Whatever the business transaction may be, it should be quick and effective.

And as it's one of your key customer contact channels, why would you not consider safeguarding it?


What are global inbound services?

Global inbound services are fundamental to any call center. While the traditional call center has now evolved into a more diverse contact center, the importance of global inbound services remains.

Global inbound services provide several access options for customers, including toll-free phone numbers, universal freephone numbers, local access numbers, as well as premium-rate and shared-cost numbers. Services use traditional time-division multiplexing (TDM) technology, via private internet protocol (IP) or via voice over IP (VoIP).

Contact centers can take advantage of the concept of a call-forward to deliver callers to strategic sites. At these sites, the appropriate language skills and product expertise are at hand to give customers the help they need, when they need it.

By centralizing services in this way, businesses are able to ensure service consistency while getting economies of scale. Customers are able to dial a number that is local and accessible to them and are offered support in their native language.

Being global, these services rely on multiple telecommunications networks. Calls often originate in one country and terminate in another. Even the biggest telecoms providers will frequently use partnerships with other network operators to offer broader geographical coverage. Additionally, calls may originate on a cellular network and terminate on an IP or TDM network. Regulatory jurisdictions and technologies often mix with differing styles of network management, so occasionally, problems can and do arise.

International call routing is complex. Therefore, phone number testing is a necessity. Businesses rely on these critical services to generate revenue and to maintain high levels of customer satisfaction.


How to test phone numbers

The type of number in question has a direct impact on how simple the process of testing the phone number will be. While local access numbers are dialable from anywhere; toll-free numbers often carry restrictions and are only dialable from within the country. While a local access number is dialable from anywhere, dialing this number from everywhere may not be a reasonable requirement for the testing team. 

For example, a Paris, France local access number might point to a contact center in Malaysia. If someone dials that Paris number from New York, intelligent network routing will identify the target destination and deliver the call without transiting through any French network. Any problem situation that impacts users in the local French networks then becomes masked. A true test design uses the service exactly as a customer would; from within that particular country.

What’s more, while dialing a single number manually might be a simple task, it does not scale well. Contact center infrastructures may have extensive dial-plans with many, many phone numbers. Manually testing all of these numbers can often be resource consuming, expensive, and produce inconsistent results. Automated methods used to test phone numbers provide more real and accurate network insights and quality assurance.


Testing phone number connection

Your first priority is to determine if your number is connecting. 

Dialing a number should always result in a ring-tone and crucially an answer! Global inbound services are generally set up so that multiple simultaneous callers can use the number. Users should not encounter an engaged tone. 

Critically, when the number connects, you will want to be sure it connects to your contact center and that it lands correctly. Unfortunately, many contact center managers will have experienced moments where their key inbound numbers were accidentally redirected to another business or even a private residence. Thankfully, automated verification is now possible.


Phone number quality testing

Once you know that your numbers are connecting, you will want to verify that the voice quality is there to support positive customer interaction.

Historically, mean opinion scoring (MOS) was used to judge telephone quality. In MOS testing, human participants would rate a phone call based on their experience of it. However, the resulting quality indication was naturally subjective.

MOS methodology has since evolved to support automated testing, however more sophisticated options have now overtaken it. For example, PESQ is the Perceptual Evaluation of Speech Quality. PESQ is an ITU (International Telecommunication Union) standard for measuring audio quality and it takes into consideration characteristics such as:

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


With PESQ, the voice quality on phone calls – mobile or fixed-lines; toll and toll-free services, VoIP or public switched telephone network (PSTN) – can be assessed to an agreed international standard. With this, there’s no ambiguity, so you know exactly how your phone services are performing.

Voice quality reporting uses a numerical scale and benchmarking which makes it possible to measure against historical performance or against other services. Efforts to improve quality can be assessed easily and objectively.


Monitoring key call attributes

Several other call attributes are also important to the contact center. 

DTMF or touch-tone is often fundamental to interactive voice response (IVR) navigation. This allows users to quickly find the service they require through keypad menu selection.

Caller ID or calling line identification (CLI) is often used to identify the caller or the geographic location from which a call originated. As a result, contact center software has some fantastic functions that leverage CLI presentation to improve business performance for inbound and outbound calls. 

While a call connection might be successful, call attributes such as these may present problems. Occasionally, when transiting international interconnects, etc. call aspects may not be maintained end-to-end. Careful monitoring ensures services can better support a contact center’s key business processes.


Reap the benefits of phone number testing

Make sure your key customer communication channel is supporting great customer conversations. For more information see our Cyara Voice Assure product page or contact our team to arrange a demo and see how you could benefit from automated phone number testing.