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January 2007
Volume 10 / Number 1

Experience Management: The Next Step for Voice Quality?

By Todd Simpson


While the combination of today’s mobile and Internet technologies is opening the door to a flurry of appealing new services, voice is still the primary reason why consumers purchase mobile handsets. Being able to deliver Internet access, email, gaming, video services, and other data services over the same handset offers multiple new revenue sources. However, even the widest variety of services will not necessarily succeed if the primary voice service is poor quality. Ensuring the highest possible quality for voice services has become prerequisite for service success.

In the mobile world, voice quality has become a make-or-break factor for subscribers when choosing a service provider. Voice over IP services will be no different, especially with the advent of WiMAX. (define - news - alert) Customers are not satisfied for long with high performance alone. Increasingly, assuring a high quality of experience (QoE) for users will become a non-negotiable requirement for every service. Experience management will increasingly differentiate carriers’ data — and voice — services.


Beyond High Quality

Internet-based businesses understand the criticality of managing users’ end-toend QoE with their products. Providing reliable, traceable, and repeatable QoE is essential — and it requires going beyond simply delivering relevant search engine results, fast response times, and current news. It requires auditing the users’ experiences and maintaining them at a high level of quality.

The emphasis on QoE is supported by industry experience. For mobile operators, JD Powers has established a direct correlation between users’ QoE and churn levels. Competition and the emergence of new service providers are providing users with many more choices for service. More subtly, as competitors adopt less restrictive long-term contracts, voice providers will have to manage “stickiness” more like their Web counterparts, improving quality, content, and community.

For voice services, content is self-generated by the user, and community is session-specific. As a result, quality quickly becomes the most obvious — and therefore important — element of the user experience. Understanding the user’s QoE on Tuesday can help the service provider ensure that it is better on Wednesday. This is where the ability to monitor the subscriber experience, determine the lifetime value of the service subscription and continuously provide incentives to remain with the service is becoming as important to voice services as it is to Internet and data services.


The Gulf Between Personalized Data and Personalized Voice

For data services, personalization is provided through a preferred level of service, pricing plan, security features turned on or off, and other networkbased service features. Web sites offer even more flexibility, enabling users to choose some personalization features and helping service providers tailor content by tracking page views, search terms, or products viewed and bought. These methods have proven successful for non-real-time services.

Voice services present a different challenge. With voice, interactive, and other real-time services, experience management becomes a more fluid, ongoing proposition and more tightly integrated with the user’s QoE. For a service provider, assuring high service satisfaction requires the ability to interact with a user during each session or to respond rapidly to quality deficiencies.


Measuring Real-time, On-the-fly Voice Quality

Today, many providers track unacceptable voice quality by counting the number of trouble tickets generated by users who are dissatisfied enough to complain. In practice, dissatisfied users are more likely to hang up and call again. If they are unhappy enough, they will switch providers. Therefore, by the time a service provider recognizes that users are experiencing poor quality, he may have lost a significant number of subscribers and have a large population of dissatisfied users who will switch the moment their contracts have expired or who are spreading negative word-of-mouth feedback.

The voice industry also has well defined standard metrics for measuring and monitoring voice quality. However, these existing standards were designed primarily for voice network planning and debugging and while they excel for this task, these measurements are not often applied in real time to every call, as required for experience management.

A new approach for ascertaining and actively improving voice quality is now possible, thanks to Voice Quality Monitoring (VQM) techniques that can be implemented within IP Multimedia Subsystem (IMS) environments. The next-generation IMS architecture merges the mobile world with the Internet world, allowing service providers to deliver ubiquitous, Internet-based multimedia services while gaining the ability to control and charge for each service, per subscriber. In IMS environments, subscribers can be recognized as individuals whose preferences can be understood and managed in order to maintain high service satisfaction and sell additional services. A significant component of any successful IMS strategy will be experience management capabilities.

Within an IMS environment, there are well-defined locations for deploying VQM solutions. For most service providers, the most appropriate location for VQM solutions is at network borders and on the media path. Usually integrated with a media gateway (MGF), or other border elements such as a session border controller, border gateway (BGF) or a media resource function (MRF) on the border, VQM solutions enable voice quality policies to be controlled from the service provider’s Service Delivery Platform (SDP).

VQM can occur at multiple levels. At its most basic, it generates packet statistics, such as those available through Real-time Transport Control Protocol (RTCP), an application-level protocol used for Quality of Service (QoS) reporting. True voice quality can be assessed using the RTCP/Extended Reports (XR) protocol, or through nonintrusive network-based tests such as ITU G.107 (e-Model) metrics. The most practical solution is to use a network- based approach, because the large number of network borders and device types makes it difficult to ensure that all components support RTCP/XR.

The goal of VQM is to monitor call quality in real time. When quality falls below acceptable levels, alerts can be generated to stimulate appropriate actions in the SDP. Measurements can be further refined to identify root causes of poor quality — delay, echo, noise, or other impairments.


Addressing Voice Quality Impairments

If the service provider actively controls network signaling and media planes, impairments identified through VQM can be addressed. Quality issues can be addressed by adjusting system parameters in the signal plane, such as QoS policies or Codecs. It is also possible to improve voice quality inline with active processing, such as that performed by a Voice Quality Assurance (VQA) solution. A VQA processing suite can actively manage items such as:

• Compensating for lost or delayed packets,
• Removing acoustic or hybrid echo,
• Matching and correcting voice and volume levels,
• Removing ambient noise,
• Terminating RTCP to pinpoint a specific quality issue.

A call can be routed or re-routed to use VQA in the media plane, typically under H.248 control from the signaling plane. With this approach, the SDP can fully implement experience management by linking VQM, VQA, and the Home Subscriber Server (HSS) together to manage and act on individualized call data. The action taken effectively personalizes voice quality, on a per-subscriber, per-call basis and may include the following:

• Fixing the current call by rerouting it, reprioritizing it, or renegotiating other system parameters, such as the Codec or Multiprotocol Label Switching priority;
• Building quality models to promote better routing and prioritization decisions in the future;
• Directly touching the customer when an unacceptable session has occurred.


Implementing Experience Management

Using VQM and VQA, service providers can take control over the users’ QoE and implement an integrated approach to ensuring consistently high QoE. An immediate positive action for a user may override any negative implications of a poor experience. Examples of positive actions could include:

  • Billing: Differentiating services based on quality. If a user has paid for premium service, then they are either not charged, or charged less, when a call falls below a specified service level.
  • Promotion: A poor experience is offset by an offer, such as free instant messaging, a coupon to a popular store or service, or other incentive. Applying consumer marketing practices used in other industries such as gaming, the long term value of the subscriber can be matched with appropriate rewards to provide a high-satisfaction voice service experience with Web personalization to a specific user.

Learning from Consumer Experience

Experience management for voice services is important. With the advent of personalized experience management across many industries such as hospitality services, online services and gaming, consumers have come to expect their overall experiences to match the level of premium they are paying for the service. As technology adoption tends to follow predictable patterns, every indication is that voice quality will continue to be of paramount importance to users. Within IMS environments, monitoring call quality and enabling experience management is achievable as well. As service providers move toward IMS, building voice monitoring and experience management capabilities into their architectures will pay off in a far greater ability to maintain high subscriber satisfaction, retention of high value customers, and lower churn.

Todd Simpson is VP of Strategic Marketing for Ditech Networks. (news - alert) For more information, visit the company online at


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