How to Deploy High-Definition Voice

By Jeffrey Rodman  |  Posted 2009-01-19

How to Deploy High-Definition Voice

Calling all IT managers: I have some good news for you if you're thinking about deploying High-Definition Voice in your organization. The move from standard narrowband audio to HD is much easier than the original shift from POTS (plain old telephone service) to VOIP to (voice over IP).

Why? Because HD Voice (also known as Wideband Audio Telephony) uses existing standard VOIP signaling, protocols and networks to carry its enhanced audio bandwidth. So, in many ways, once you've made the move to VOIP, you've already done most of the legwork in deploying HD Voice.

HD Voice makes talking on the phone far more productive and much more pleasant than what you're used to because it restores the two-thirds of the audio spectrum that conventional phones take out. HD Voice makes talking on the phone sound as if you're in the same room as the person on the other end. If you haven't experienced HD Voice yourself, think of High-definition Television (HDTV) or High Definition Radio (HD Radio). Once you've heard and seen the difference, you realize exactly what you were missing. As a result, HD Voice is gaining traction in the communications industry.     

The good news for IT managers is that HD Voice maintains compatibility with your existing systems, so the transition is quite straightforward. In fact, it's relatively simple because the protocol is still standard Session Initiation Protocol (SIP). Even better, the data rates are generally comparable to standard G.711. This is a little-known fact-many IT managers incorrectly assume that bandwidth requirements are higher but they are not, so take note!

But, as seamless as the transition may be, there are always ways to smooth the transition process further. So let's take a look at some of the most important points to consider, starting with some hardware considerations.

Five Hardware Considerations

Five hardware considerations

1. Be sure your PBX is HD-aware. If it's not already, this is a simple software update to a VOIP PBX. What happens is that "G.722" (by far the most popular wideband VOIP codec today) is added to the list of allowed codecs. Most major PBX vendors are already shipping (or are soon planning to) G.722 compatibility. 

2. Be sure that any new VOIP phone purchases are rated for HD Voice. Networks are rapidly moving to HD Voice and phones have a typical service life of five to 10 years-which means that a narrowband phone bought today will be obsolete long before it has been fully depreciated. A narrowband-only phone will also be the poorest-sounding participant in a group HD conference. Take advantage of the HD Voice and wideband phones available from multiple vendors today.

3. Get HD Voice quality-not just "G.722-compatible." For the same reasons that feeding an HD video signal to an old television set may give a picture but it will be the same old blurry video, HD Voice needs more than just a G.722 codec. HD Voice means HD microphones, a great speaker subsystem, a thoughtful acoustic design and tight integration among software, hardware and mechanics. And if the phone has a built-in speakerphone, it's even more critical. Just claiming HD Voice compatibility doesn't mean a phone will deliver full HD Voice performance so compare and listen for yourself. 

4. Confirm that HD Voice phones can be future-upgraded with new codecs. Today's G.722 (7kHz, 64Kbps) will soon be augmented with G.722.1 for full 7kHz HD Voice quality at less than half the data rate (7kHz, 16-32Kbps), so be sure that new phones have room to grow.

5. Convert those speakerphones. The advantages of HD Voice are most overwhelming in group conferences where distractions and lousy room acoustics-a lot of people, a lot of noise, people who don't speak up and a wide variety of accents-are an epidemic. That open-air setting really spotlights the HD difference, even more than on a handset. Switch from conventional narrowband speakerphones to HD Voice over HD connections and users will be astounded.

Four Network Considerations

Four network considerations

1. HD Voice uses an added codec in a VOIP phone but is fully interoperable with standard narrowband SIP phones. This is because HD Voice adds another available mode but doesn't remove the ones that are already there; the phone can still support whatever narrowband codecs and connections you had before. If an HD phone calls a narrowband phone, they'll connect in narrowband and work fine. If it calls an HD phone, they can connect in wideband-and will sound a whole lot better than what you're used to.

2. Check that the call routing supports HD Voice. The public switched telephone network (PSTN) today hasn't yet moved to HD, so even if both endpoints are HD-capable, selecting a route over PSTN will force the call down to narrowband. Yes, they'll connect, but they'll connect in conventional narrowband because they're throttled by the PSTN network. To avoid this, routing across private networks and IP networks can preserve full HD quality. So give careful consideration to your dial plan and IP trunking to maximize the extent to which connections can be end-to-end HD Voice.

3. Check that the LAN and WAN can handle G.711 data rates. G.722 uses the same bit rate for HD Voice as G.711 uses for narrowband audio (64Kbps or about 80Kbps with network overhead). But if a user has implemented a high-compression codec such as G.726 or G.729 for a narrowband VOIP system, HD calls could increase network bandwidth. Especially in such systems, the bandwidth and WAN device capacities-including queue and buffer sizes-should be examined.

4. Enable HD Voice features. The most important feature that people will need, of course, is bridging-and the more people on a call, the more important it becomes to have HD Voice connections because the sound gets muddy so easily on conference calls. An easy win-win is to consider starting with an HD Voice-enabled conferencing service provider.

Most important user consideration

Lastly, educate the users. A favorite story about HD deployment is an organization that equipped all of their desktops with wideband phones and enabled people to call desk-to-desk in HD. But when people called out to the PSTN, the calls were in narrowband. As a result, IT received complaints that the PSTN calls sounded bad by comparison. The way they solved this was by turning off HD completely so users had nothing to compare to! 

The moral of this story: Educate your users about HD Voice. Let them know that some calls will not be HD (but no call will sound worse than it did before) because the networks are still catching up. It's like talking to someone who's on a cell phone-you can have the best phone in the world and they'll still sound lousy.

But the world is rapidly moving to HD Voice and that's why the right decision is to be thinking future-proof.

 Jeffrey Rodman is Co-Founder and CTO of the Voice Division at Polycom. Jeffrey has been at the forefront of audio and video communications for most of his career. Following a BSEE Cum Laude and MSEE in Electronic Engineering from CSUN, Jeffrey spent six years developing and enhancing video and test capabilities for military-guided missile systems for Hughes Aircraft Company. During this time, Jeffrey also created a novel approach to sound synthesis that formed the foundation for his Master's thesis. Jeffrey also co-founded Specialty Video Systems to market digital video effects to the entertainment industry.

In 1980, Jeffrey joined Harris Video Systems where he became Director of Engineering, pioneering new digital video processing systems for broadcast and production applications. In 1984, Jeffrey was recruited to build a hardware engineering organization and implement a revolutionary architecture for the then-new startup PictureTel (later PicTel), building the foundation for a family of systems that has transformed the videoconferencing industry. Jeffrey continued on as Director of Hardware Development through PictureTel's formative years.

Jeffrey co-founded Polycom in 1990, and has been instrumental in the realization of Polycom's iconic products for voice, video, network communications and other media. He can be reached at 

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