High-definition voice

01 January 2011 |


High-definition voice is a high-fidelity, life-like alternative to traditional, circuit-switched telephony, which is still restricted to the limitations established in 1937.

 The superior user experience it delivers is prompting many wired, wireless and Web 2.0 service providers to upgrade to HD voice. By 2014, the HD voice market will be worth $3 billion annually, according to In-Stat, an independent analyst firm.

In a sense, HD voice is like HDTV: HDTV requires not only a HD TV set, but also HD production, HD signals, and a HD set-top box from a cable operator or satellite provider.

Likewise, HD voice requires more than just a HD handset. To fully deliver HD services, a provider needs an ecosystem of HD-enabled components: devices; network capability; and scalable, cross-network IP interconnection, including support for wideband codecs and transcoding.

The HD voice ecosystem


Each part of that ecosystem plays a role in delivering an aural experience noticeably superior to PSTN telephony and wireless. Major audio-conferencing and video-conferencing vendors, such as Polycom, have spent the past few years adding HD voice to their products because sales show that enterprises value full-fidelity, life-like audio. The foundation of HD voice is VoIP, which gives networks and endpoints the option of using wideband codecs, such as G.722, AMR-WB and Skype’s Silk. Traditional, “toll-quality” telephony uses G.711, which samples audio at a range from 300Hz to 3.4KHz. Typical wideband codecs such as G.722 sample more than twice as much.

Surprisingly, many of these new HD codecs usually require the same or even less bandwidth than traditional voice codecs.

A higher sampling rate preserves more of speech’s nuances, so high-frequency consonants such as “s” and “th” aren’t lost during encoding. The absence of these consonants forces callers or video-conference participants to ask people to repeat themselves and can be a major communications barrier. Eliminating that annoyance is an important justification for upgrading to HD voice.

Launching HD voice services


Mass-market consumer and enterprise adoption of HD voice requires HD-enabled IP interconnection, the framework that lets HD voice calls – and other kinds of multimedia communications, such as HD video and messaging – traverse multiple service provider networks. An all-IP connection, from one caller to the other, bypasses the PSTN, which can’t support HD. Without all-IP interconnection, an operator’s HD voice service is limited to its network, instead of being able to connect with HD voice customers on other operators’ networks.

HD voice providers can use a carrier ENUM-based, HD-enabled interconnection hub to enable fully-optimised, end-to-end HD calls to HD-capable service providers. Hub-based transcoding also effectively preserves HD quality when multiple wideband codecs are involved in a call, such as from a mobile network using AMR-WB to a wired network using G.722/G722.1.

Service differentiation


Over the past decade, VoIP has helped commoditise voice by creating low-cost, sometimes-free alternatives to circuit-switched wireline and wireless telephony. As a result, service providers have scrambled to decrease overhead costs so their voice services – both circuit-switched and VoIP – can be priced competitively.

Who’s interested in HD voice?


HD voice’s life-like quality enables service providers to compete on something other than price, helping reduce churn and customer-acquisition costs and, in some markets, potentially giving operators an opportunity to charge a premium. The better the user experience, the longer customers will talk and thus the more they will spend. Skype, US operators such as 8x8 and Ooma, and mobile operators such as France Telecom, Orange UK and 3 (UK) are a few examples of providers using or planning to use HD voice as a market differentiator.

Cable operators are also showing high interest in HD voice as a way to distinguish their telephony services from traditional telcos in the consumer and enterprise markets. HD voice-enabled IP interconnection hubs are particularly attractive to operators, including cable providers, that prefer a scalable approach to direct connections with other service providers. Rapidly growing operator participation in HD voice-enabled IP interconnection hubs is one indication of how and why HD voice is poised to become a mass-market service for consumers and enterprises worldwide.