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High Definition Voice (HD VoIP)

petermaughan
Grafter
Posts: 83
Registered: 06-04-2007

High Definition Voice (HD VoIP)

Hello,
An ADSL link provides a much higher bandwidth than a plain old pair of copper wires that was all that was available to the original telephone designers, so why can't we get really high quality sound from VoIP? 
With this question in mind I've been Googling the Internet and find that there is a presently lot of interest in High Definition VoIP.  In particular, codec G.722 and others give twice the bandwidth of the commonly used G.711.  G.729 has less bandiwith than G.711, I've leaned, and has no chance of reproducing good quality speech.  On the other hand, apparently Skype and some of the other computer based online voice services already use high definition codecs.
So, what do others think?  And does PlusNet have any plans to support and encourage the use of high definition codecs.  It seems to me that if VoIP has the potential to be better than POTS then that is where the future must lie.
Peter
19 REPLIES
Community Veteran
Posts: 1,139
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Registered: 20-07-2007

Re: High Definition Voice (HD VoIP)

Hi Peter
It sounds interesting but I can't say that I can see the need for a higher quality telephone service. Also most (all) of the people I ring are on BT landlines so I assume there would be no increase in quality for these calls?
Bob
petermaughan
Grafter
Posts: 83
Registered: 06-04-2007

Re: High Definition Voice (HD VoIP)

Hi Bob,
I've been following your Gigaset thread on this forum with interest.  I understand that Gigaset is one of the forerunners in HD VoIP.  By offering free calls between Gigaset users via Gigaset.net then Gigaset VoIP users get the benefit of high definition voice end-to-end.  But I see on your Gigaset thread that you say you haven't tried it.  It is certainly one of the problems being an early adopter of new technology that it's not much good until the take up reaches a certain level, e.g. email wasn't much fun to start with but now everybody's using it.  That's why an ISP such as PlusNet needs to promote HD VoIP.  And with the backing of its friends at BT it shoud be well placed to take a lead.
Peter
Community Veteran
Posts: 6,263
Thanks: 433
Fixes: 40
Registered: 30-07-2007

Re: High Definition Voice (HD VoIP)

Peter,
I thought ( may be wrongly ) that Gradwell ( who supply Plusnet Voip ) do already support the use of G.722. So if you make a Sip->Sip call and both ends support G.722 then it should already be possible to get HD Voip calls. I guess the problem is going to be, as Bob says, that the vast majority of calls are going to go through a PSTN->voip gateway in one direction or the other and there is no point at the moment in these gateways using G.722, as the PSTN quality just isn't up to it. Maybe when we get voice on 21CN it may be possible ?
Ian
itsme
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Posts: 5,924
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Registered: 07-04-2007

Re: High Definition Voice (HD VoIP)

Quote
The Codecs that Gradwell support are:
G711, There are two variations of this standard a/law and u/law. The G711 algorithm encodes non-compressed speech streams running at 64 kbps (approx 80 kbps when IP overhead added). Because the G711a/law codec is used by the European public telephone network, using this codec reduces the amount of transcoding required to pass the call from end point to end point and is therefore the preferred codec for best quality VoIP calls when connected to a UK network. G711u/law is used by the US network.
G729, There are two variations of this standard G.729 and G.729 Annex A. The G729 algorithm encodes non-compressed speech streams running at 32 kbps. This codec tends to be used in environments where bandwidth is an issue but should not be considered a permanent fix for this problem. In order to measure the quality of the vocoders there is a measuring system called the Mean Opinion Score or MOS. The MOS functions on a scale type measuring system from low to high (0 being low and 5 being the highest). There are many software packages available that will provide MOS scores based on a series of set tests that will use a known connection and a specific sound file to analyse your network performance for VoIP services. For example http://www.testmyvoip.com by Brix Networks.
puddy
Grafter
Posts: 1,571
Registered: 10-06-2007

Re: High Definition Voice (HD VoIP)

I just wished we could make video voip calls too
Puddy
petermaughan
Grafter
Posts: 83
Registered: 06-04-2007

Re: High Definition Voice (HD VoIP)

Thanks to everyone for the replies.
I had a look at BTs 21CN website.  A search on "High Definition Voice" didn't produce any results.  Digging deeper, I got to a page headed " 21CN - Key characteristics" and on sound qualitiy it ended up by saying "The bottom line is that no-one should notice any difference. "  To my mind, that is not good enough.  What is needed is a significant improvement in sound quality by carrying wideband voice signals.
I had a look at Gradwell's website.  They say that calls routed via their Asterisk system are limited to G.711 and G.729 codecs but if you are using the Single Line account you can use any codec that the originating and destination devices can support.  Does anyone know which type of account PlusNet users are allocated to?
I see that there are a number of soft-phones available on the Internet for download that do support the wideband codec G.722.  Possibly this would be a way for end-users like myself to try out HD Voip.
One thing has become clear to me from this thread; service providers make their money from interfacing with the narrowband PSTN, which is chargable.  VoIP to VoIP, which has the potential for wideband voice, is offered free of charge.  So the present financial model of VoIP will not encourage the spread of High Definition Voice; we end-users will need to demand it.    Peter
Simon_M
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Registered: 05-04-2007

Re: High Definition Voice (HD VoIP)

Quote from: petermaughan
One thing has become clear to me from this thread; service providers make their money from interfacing with the narrowband PSTN, which is chargable.  VoIP to VoIP, which has the potential for wideband voice, is offered free of charge.  So the present financial model of VoIP will not encourage the spread of High Definition Voice; we end-users will need to demand it.     Peter

You have hit the nail squarely on the head there Peter. The SIP protocol has enormous potential for all sorts of innovative point to point communication systems, of which VoIP is but one example, but because no one has worked out how to make money out of it, development & take up has been very slow.
itsme
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Registered: 07-04-2007

Re: High Definition Voice (HD VoIP)

As this thread is called High Definition Voice I wonder why G722 will improve the voice quality that we have now using G711?
The frequency range of voice is 300Hz to 3400Hz, G711 sample at 8kHz and G722 sample at 16kHz.
The Nyquist–Shannon sampling theorem states that perfect reconstruction of a signal is possible when the sampling frequency is greater than twice the maximum frequency of the signal being sampled. Therefore sampling at 8kHz will reconstruct signals up to 4kHz without degradation and this is higher than the frequency voice range.
petermaughan
Grafter
Posts: 83
Registered: 06-04-2007

Re: High Definition Voice (HD VoIP)

Hello itsme,
I think that in fact there are higher frequency overtones in the human voice which need to be reproduced to make it sound natural.  I think that "S"s and "T"s in particular have a higher frequency component.    I've read that the sound produced by the human voice can include frequencies up to 14kHz.
Certainly when listening to the radio it is easy to distinguish a programme-maker's voice with a full frequency range coming from the studio and someone calling in from outside on a telephone, say on a phone-in programme, where the typical narrowband sound of a telphone call is obvious.  I've read that producers of radio plays will simulate a telephone call by reducing the frequency range of the recorded sound.
Peter
itsme
Grafter
Posts: 5,924
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Registered: 07-04-2007

Re: High Definition Voice (HD VoIP)

Is it the G711 codec that make the voice quality on some calls poor or the microphone in the headset?  I would go for the latter as I have heard some pretty poor PA systems which don't use any codecs and good sound quality on conference telephone calls when using external mics and speakers.
petermaughan
Grafter
Posts: 83
Registered: 06-04-2007

Re: High Definition Voice (HD VoIP)

Hello itsme,
It's a good point about needing a high quality microphone and earpiece speaker.  I think that many phones haven't bothered with good quality components because the signal would be lost in transmission over the PSTN.  Here is a link to an article about a Voip phone manufacturer, now offering codec G.722, that has increased the quality of the components on its most recent models to take advantage of the higher bandwidth available.
http://www.sipy.com/2009/09/03/aastra-launches-hd-voip-audio-called-hi-q-takes-on-polycom/
Peter
puddy
Grafter
Posts: 1,571
Registered: 10-06-2007

Re: High Definition Voice (HD VoIP)

Had a look on my Grandstream GXP2000 it offers G722 (wide band) but my later Grandstream GXV3005 does not off G722 at all
Cannot look on my Gigaset 460ip phone because I cannot log in to it with the latest edition of ms internet explorer.
I know nothing about which codecs I should be using.
I can make video calls on my Grandstream GXV3005 using Orbtalk payg Voip service but not Plusnet voip service  plus I dont know how plusnet voip service blocks video calls and why Undecided
Puddy               
petermaughan
Grafter
Posts: 83
Registered: 06-04-2007

Re: High Definition Voice (HD VoIP)

Hello all,
Here's an interesting item on Youtube:


Peter
petermaughan
Grafter
Posts: 83
Registered: 06-04-2007

Re: High Definition Voice (HD VoIP)

Hello All,
I thought I would enliven this topic.  I'm still interested in HD Voice and here is a recent paper by Ericsson.
http://www.ericsson.com/res/docs/whitepapers/WP-HD-voice.pdf
Lots of people are interested in HD TV these days but we mostly still make do with telephone calls with a very limited sound frequency range.
I see that mobile networks are starting to offer HD Voice, too:
http://www.bbc.co.uk/news/technology-11138503
Has anyone had recent experience of HD Voice over PlusNet VoIP, or any other service?
Peter