It makes me crazy when people start offering misinformation as if its gospel. Poor information wrapped in a nice looking blog is genuinely harmful. That’s what I found in the VOIP School post from June 17th. The title of the post is “HD Voice. The Future of VoIP?
Why so agitated you ask? Well, allow me to explain, based largely upon a comment that I left for their consideration. I’ll quote the more egregious bits from their June 17th post:
“HD transmits from about 50 Hz to 7,000 Hz”
Yes, but that’s the absolute minimum, worst case that anyone would consider a HDVoice call. Typical of G.722. Some codecs support audio bandwidth > 20 KHz. Yes, music quality.”
Additionally, since HD voice transmits more frequencies it takes up more bandwidth.”
That’s patently false, or at best misleading. Of the many wideband codecs out there only a few use any more bandwidth than plain old G.711 that we call PSTN “toll quality.” G.722, the oldest and most common wideband codec in hardware uses the exact same 64 kbps before packet overhead. Most use much less, some dramatically less.
Want to know more about the specifics of various wideband codecs? Here’s something I posted a few months ago; “Myth Busting HDVoice: Frequency Response vs Data Rate“.
“Also, users may have to invest in HD phones to get their full money’s worth.”
What kind of mealy mouthed wish-wash is that? If you want to experience a wideband call using a desktop phone you will need to buy one. That’s just common sense.
If you find a soft phone on your PC an acceptable alternative you might have to buy one of those. There are also open source & freeware options in that area. Some, Like PhonerLite for Windows, are wideband capable.
“While HD compatible phones do exist, some argue that they don’t deliver full HD voice quality.”
More drivel. You might have had a point, but failed to make it accurately.
Most wideband capable phones deliver real wideband quality calls. A few of the very cheapest might support a wideband codec for marketing purposes. It looks good on a tech sheet. But those same very cheap phones may not have the physical hardware quality to deliver a great sounding call.
The old Grandstream BudgeTone 200 is the classic example of this. While it supports G.722 you only hear an HD call on this phone using a headset. This is a simple case of getting exactly what you pay for.
“Even then HD to HD calls will be worthless if they have to travel over a traditional land line.”
Ahem, if the call path is via the PSTN – “a traditional land line” – then by definition it’s NOT an HDVoice call. HD calls require a pure IP media path. IP end-to-end. That usually means dialing by SIP URI.
In my case that means I have the pleasure of wideband calls between my associates desks. Also calls between offices routed via our WAN. Also calls home from a soft phone on my laptop to the Gigaset phones at my home.
We especially appreciate conference calls where its just simply easier to understand what’s being said. Heck, my dogs even recognize my voice over a wideband call to a cheap little ClearOne Chat 50 speakerphone plugged into my wife’s PC.
I applaud your effort to be informative with this site. To be credible you need to do your homework about topics like HDVoice. If you’re not speaking from personal experience using HD then you’re not well positioned to comment.
This post has very little useful information except to express your personal lack of enthusiasm about HDVoice.
Now, moving on to the July 2nd followup post entitled “HDVoice – The Technical Stuff.”
While not as negative in tone as the first post it continues in the offering of marginal quality information.
“As HD voice continues to become more prevalent, the industry will push for a single wideband codec.”
There may be a desire for a single wideband codec (Boy is there!), but it will likely never happen. Just as the PSTN lives on with a handful of more common codecs (G.711, G.723, G.729, G.726, GSM, AMR) wideband voice will likely get down to a small subset set of what is currently being considered. My guess is that we’re going to live with perhaps 3 or 4 in the end.
Some companies, like Audio Codes, will benefit from the use of multiple codecs since it creates demand for media gateways capable of of wideband transcoding. Even their new line of HDVoip desk phones only supports G.722 at present.
“However until then, it’s important to do research on the type of codecs that are integrated into your HD phones.”
That’s difficult. There simply aren’t very many wideband codecs deployed in desk phones at the present time. G.722 dominates and can be found in phones from every major vendor of IP phones.
The exception being cell phones. There are extremely few cell phones at present that support wideband, but where they do AMR-WB (aka G.722.2) and EVRC are the most common codecs.
The apparent gulf between the mobile and fixed line world is why I expect that we’ll never get below 3-4 codecs. The GSM folks will settle on one and the CDMA proponents will pick another. Then the wireline industry will pick something more ideal for their needs. That’ll be 3-4 codecs at the end of the day.
Where there are a myriad codecs offered is in the realm of soft phones. But my sense was that you aren’t really talking about that. Are you?
“There is more to HD voice than the codec.”
Haleluia! That’s very, very true!
“While HD compatible phones exist it is probably a better idea to go with HD capable phones. “
I don’t see a solid reason for the distinction between “HD compatible” and “HD capable.” I see no marketing for compatible vs capable in the various manufacturers literature.
Snom supports G.722 in all of their 300 series phones, but requires an upgraded “KlarVoice” handset to truly deliver the goods. Maybe that’s what you mean, but they’re the only one. There’s no trend behind that.
I don’t think any manufacturer is trying to trick people. It’s simply a matter of getting what you pay for. If you buy a very cheap phone don’t be too surprised if it looks, feels & sounds like a cheap phone.
“Second, it’s important that your service provider can properly transmit HD voice. Any call made outside the company that has to jump on a PSTN won’t be HD quality, but by choosing the right provider calls made in office or between company branches can be guaranteed HD. The trick is to make sure that your provider offers end-to-end SIP. SIP, or session initiation protocol, checks each of the end points to see what codecs they have in common and then transmits the call in the highest possible quality. In this case, the use of different HD phones or soft phones doesn’t have too much of an effect on HD call quality.”
There’s something about this that just isn’t clear. Yes, SIP is important. An end-to-end IP call path is critical to wideband calling. But you don’t even mention the concept of SIP URIs, which are a key aspect of making wideband calls. Nor do you mention hosted IP-PBX solutions, which are a great low-cost way to deploy HDVoice.
BTW, the term HD is getting thrown about in telecom with reckless abandon. What we’re talking about here is “Wideband IP Telephony.” HDVoice is a registered trademark of Polycom.
I truly do appreciate blog sites that try to introduce technical matters to the uninitiated. It’s a sometimes daunting task, and never easy. One of the things that motivated me to start writing this blog was time spent answering questions in public forums like VoIP Tech Chat on DSL Reports. I still do that as a matter of routine. See here, here, here and here for examples.
What causes me such consternation is the fact that VOIP School is a nicely done site. In fact, it’s listed as part of AllTop. That would seem to impart some serious credibility. Perhaps this topic was just a stretch for the author.
Anyone even vaguely interested in wideband VoIP should come on by the VoIP Users Conference one Friday and get some first hand experience using the techology. They’re a tremendous group of very experienced VoIP aficionados who are happy to help interest folks starting out with wideband voice.
And most of them are a lot less irritable than I might appear to be.