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July 2008 | Volume 11/ Number 7
Packet Voice Over Wireless

Is It Time for Wideband Telephony?

Do you care how good your phone sounds? It seems that most people don’t. In an earlier column I wrote that the popularity of mobile phone service in the face of its lousy sound quality shows that customers value mobility over audio performance, but not that sound quality is unimportant.

A May 2008 study by Keynote found that wireline voice subscriptions in the U.S. declined by 10 percent in 2007, while cable VoIP subscriptions grew by 75 percent. This study also found that the quality of VoIP calls is inferior to that of wireline calls. In other words, customers value price over audio performance, too.

VoIP can sound vastly better than traditional voice, because it can use wideband codecs, which convey audio frequencies from 100 Hz to 7 KHz, compared to 200 Hz to 3.4 KHz on traditional phones. Skype (News - Alert) is the poster child for wideband codecs, which can make it sound great. Skype isn’t much help to businesses though, because business phone systems are still based on PBXs.

The uptake of wideband codecs in PBX (News - Alert) systems has been glacial, for several reasons, one of which is the network (or fax machine) effect — a wideband phone is no help unless the phone at the other end is wideband, too. Plus they have to support a common wideband codec, the connection between them has to have adequate bandwidth and reliability, and it has to be IP all the way, with no hops on the PSTN.

Supporting a common wideband codec is more of a challenge than one might expect. The standard codec that will prevail in the future, AMR-WB (also known as G.722.2) is impeded by complicated and costly licensing; the most widely deployed wideband codecs are proprietary: Microsoft (News - Alert) RTAudio which is included with Windows, and Skype’s SVOPC.

Business phone systems are beginning to overcome this challenge. Cisco, Avaya, 3Com, Siemens and Panasonic (News - Alert) all now have wideband IP phones in their product lines, and wideband IP phones are also available from non-PBX manufacturers like Polycom, Grandstream and Snom. All of these are interoperable in wideband, since they have the same codec, G.722.

High quality IP connections from end-to-end are easily doable for calls that stay on the LAN, but if a call goes outside the company it is virtually certain to cross the PSTN at some point. There are several initiatives aimed at fixing this, most notably ENUM, which piggybacks on the DNS infrastructure and translates standard (E.164) phone numbers into IP addresses.

As end-to-end IP calls become more common, so will the use of wideband codecs. The audio quality of business phone calls will improve for the first time in decades. IT

Michael Stanford (News - Alert) has been an entrepreneur and strategist in Voice-over-IP for over a decade.

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