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Friday, October 21, 2005

Performance Matters for VoIP

In his earlier post on Web Usability: A Simple Framework, Chris Loosley considers what requirements web sites must fulfill to satisfy users. The simple framework he proposes breaks down the principles of Web Usability into four distinct areas: Availability, Responsiveness, Clarity, and Utility. To attract and retain users, Web sites must satisfy these four needs.

As the VoIP industry rapidly grows and expands, it too needs to address issues of usability in order to attract and retain new customers. Performance matters when it comes to VoIP usability, and to succeed in the marketplace a VoIP service offering must satisfy the same basic needs as a Web site:

Availability is an obvious requirement. The traditional telcos have set very high expectations for the market. Using a phone on the Public Switched Telephone Network (PSTN), users expect to be able to get dial tone and place a call 99.999% of the time.

Responsiveness is a critical performance factor in VoIP service satisfaction. Every VoIP call has a certain amount of delay, measured in milliseconds, for the audio to travel over the virtual circuit between phones. Excessive delay causes conversational disruption that can quickly lead to user dissatisfaction.

Clarity in phone calls is also an important performance factor. As Chris describes it, clarity describes a service that is "simple and natural to use." A "simple and natural to use" VoIP call is one in which the audio sounds clear and natural. Calls need to avoid audio defects that get in the way of understanding the speaker on the other end of the line.

Once the other three needs are met, the quality of Utility addresses whether or not the VoIP service actually delivers the value, features, and customer service that the customer looks for. Is international dialing easy to do? Does the voicemail system meet the customers' needs? Is the billing process accurate and easy to understand?

Customer satisfaction in VoIP systems involves the same Service Level Management requirements that web sites must meet. Of the four qualities described above, three -- Availability, Responsiveness, and Clarity -- fall under Service Level Management. This is different from Web Usability, where Clarity is a more qualitative aspect of the total customer experience. For VoIP, great strides have been made in converting the qualitative assessment of how clear a call sounds to the human ear into a quantitative measurement that can be automated and managed as a service level performance metric.

Although VoIP service performance is measured differently from Web site performance, providers of VoIP services have just as much at stake in managing their service level performance. VoIP service level measurement and management are rich topics that I plan to cover in future posts.

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