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Cable VoIP Sounds Better Than Some Landlines
A. G. Bell writes "A recent study that looked at the quality of phone calls came up with some surprising results. Ars Technica reports that while 'traditional' VoIP call quality lagged behind landlines, service from cable ISPs was much better because of their use of PacketCable: 'VoIP from the cable companies actually surpassed the traditional phone network in reliability, meaning that the service was more often available and connected calls without dropping them. Cable providers also led the way in audio quality; the top firm in Keynote's study actually turned in an MOS of 4.24, above most real phone networks.'"
Given the bandwidth of a cable (or any other broadband) connection I don't see why this should be surprising. Since a standard phone line needs to be upgraded for ADSL anyway, clearly the throughput with VoIP should be better than POTS.
Burns: We're building a casino!
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In my little hometown they still use the original ancient phone lines that leak signal like crazy. In fact, you could easily hear other conversations if you paused while talking on the phone. I'd guess that a majority of towns are using lines that are at least 30-50 years old still.
...but how long until the major phone companies (Bell-South, AT&T, etc) start to QoS the packets from competing cable ISPs to lower the quality compared to traditional land lines?
This seems to me like the ISP gets an advantage because of this PacketCable thing -- something I'm sure they will not be licensing to their VoIP competitors like Vonage. Not surprisingly, these 'other' VoIP providers fared worse then the ISP-provided VoIP service. I'm sure the ISP will tout how its own Voice service is better than the competitors, and I would also wonder if they take additional steps to degrade the quality of their competitors. Oh yeah, I just tried to get cable internet alone (without TV or voice), and they acted very rapidly to filter the analog TV out, cut my speed from 6 to 4, and jacked up the price to $60/month. Assholes.
I have a Cisco 7960 at home and a polycom 601 at work and they both toast landlines. We sell voip systems based on asterisk and a lot of it depends on whether the phone is full duplex, half duplex, if you use a switch or a hub, your isp. My isp is time warner and is very good. My same phone on my moms comcast would suck at 6pm when it is congested. VOIP on a pri definitely rules though if you have a full duplex phone. even on speakerphone.
Contrary to popular belief, Unix is user friendly. It just happens to be particular about who it makes friends with.
...anecdotal evidence for you:
I'm using a Cogeco* VoIP phone, and it's awesome. It's clear as a bell, whereas the Bell POTS connection that I had previously had enough static on the line that it made it tremendously hard to hear the conversation. For the longest time I thought it was the handset...You can imagine my surprise when I switched over, used the same handset, and found that all that static had disappeared.
* - I don't work for Cogeco and frankly couldn't care less if they survived or went belly-up tomorrow... but they're a cable company and it fits with TFA...
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Typically, a well designed Digital Phone network will provide end to end QoS to protect calls from pops, clicks and whatever other impairments are associated with IP Data communications. Owning the network from the Customer to the PSTN Gateway (or even a completely protected IP Trunk) ensures full control over the call quality. Since the technology itself has a certain level of error survivability due to FEC in codecs, the call will not suffer from electrical interference typical with the worlds aging twisted pair networks. This provides a nice clear call, which isn't surprising. Providers such as Vonage have to play with many providers between their customers and PSTN gateways, most of which, they have no control over.
I forgot where I saw it (it might've been here), but not too long ago I read a minirant where the person was comparing the phone service of yesterday to the service expectations of today. Admittedly it's two different types of service (landline vs. cell), but we've gone from advertising phone service so clear where you can supposedly hear a pin drop to making a big deal out of being able to hear the person at all. Just a little food for thought...
:)
I'm still going to keep my POTS line. It's my security blanket.
Ouch.
Anyway, this article is pointless. Gay and moot. Has nothing to do with cable networks. It's just dealing with the modulation/bitrate that the cable companies went with. If I wanted to run another VoIP over the cable line, I could make it better or worse.
This matches my experience. We have Vonage via cable modem. Our neighbors who have POTS have had a number of lengthy service outages within the last yeur or two, whereas we've never had any. As far as audio quality, it just sounds normal to me.
The only problems we've had have been with integration among the various parts of the system, and I guess that's not surprising, since it is multiple systems working together, rather than a monolithic system like Ma Bell used to be. The big problem we had was that every time someone would leave a voice mail on Vonage's system, our internet connection would die, and we'd have to power cycle to get it back up. The solution was simply to stop using Vonage's voice mail (which was klutzy anyway), and switch to using the answering machine that was already built into our phone anyway.
A lot of people express concern about the 911 issue. Vonage now has automatic address recognition (if you set it up with them, which they try very aggressively to make sure you do), and from what I understand, there's no real data on reliability of Vonage's 911 versus reliability of POTS's 911. It's apparently quite common for POTS's automatic address recognition to fail, and for that reason, the first thing they always do when you call 911 is ask for your address anyway. The thing that does bother me a little about the 911 issue, regardless of the service provider, is that you can't test it without making a false 911 call. I don't like the idea of an important safety system that you can't test.
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I have been using Comcast's Phone service for the past several months. Apart from the fact I incurred a phone number attached to someone with credit problems, the actual service of the phone is horrible. It sounds like I'm on a cell phone with a bad connection. Lots of static. On a few occasions, people have been unable to reach me (my phone never rang).
Overall, I rate my Comcast experience as a 2 out of 10.
I wonder if they were truely comparing "Cable VoIP" or the concept of providing dial-tone/phone service over cable. Things may have changed since I was working for a cable provider, but back in the day... Service would be provided by attaching a box to the side of the house. The service had an allocated set of "Channels". Just like channels are allocated in the normal cable spectrum that to deliver things like HBO and ESPN. The range used for TV never overlapped with Voice or Data. The range for Data never overlapped TV or Voice, etc.. (You get the picture). Because of this there's no competing for bandwidth with all three products and the part allocated for voice calls was of sufficient bandwidth. Unlike the vonage box I have now, if I start downloading torrents or pushing the upload/down rates on my connection some other way I have the potential of breaking up my VoIP call. With voice over cable provided services (not necessarily Cable Voip) this wont happen. Unless of course there's noise on the lines affecting the freq. range used by the boxes.
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Comcast drops their fiber so deep into neighborhoods around here its almost fiber to the home. On top of that, the cable around here is all burried so it avoids storm related outages, and lets not forget the biggest factor: voice is digital all the way to the home, the voice quality of course is going to be clear. There isn't a single run of analog signalling between the user and the cable company, thats why its so clear and such a predictable result.
:) Move along
Nothing to see here
www.atacomm.com - The Leader in VoIP Product Distributi
They must not have checked my area. On average my cable line is down 2 days a month. Last month it was down for a week. The local cable company just responded "Sorry, we are working on it." (Time-Warner Cable) No ETA, No reason as to why it was down, No other information.
Heck the last time my ISDN line went down was 3 years ago. VOIP is nice but with the issues that my local cable has keeping the system up and running, Ill wait.
I am using shaw for phone in canada over Cable, and I have to say it is way more convienent that the same offering from Telus. The value that shaw offers is unsurpassed in that it includes unlimited long distance in North America within the monthly fee. My monthly bill for this service is around $50 CAD each month. I am from the US so, my long distance bills with Telus used to be quite high, even using call arounds and different calling plans. I am officially a believer. Sound quality is great. Never a dropped call, ever, not even using 3 way.
Except at work, I haven't really used a landline in years. Let alone depended on it. My mobile phone works fine for when I've really needed it.
You are kidding? A whole 4.24?! That's amazing!!!
WTF is a MOS? Somebody slap Zonk.
I recently switched one of my pots lines over to cable,
and was pleasantly suprised when Charter added an additional
telephony modem to the mix, and didn't parasite on my
other bandwidth. It's been 2 months without a glitch, and
I will be switching all but one (ya never know) of my other
lines RSN.
Here in India I use Vonage's VoIP @ the lowest bit rate setting of 32 kbps (on a 256kbps internet)& still the voice quality is better than ordinary landline.(& its up 24x7)
Add to that there is no 1 sec timelag-delay in conversations through VoIP on calls to US .
Wincopy
This is a real bitter subject for me. I (try to) use Vonage over Comcast's internet service, but I get daily service outages, dropped calls and overall poor sound quality. I do not blame Vonage for any of these problem. Whenever I call Comcrap to complain about their internet service they always ask what I use the internet for: surfing, e-mail, etc. When I reply with Vonage, they always try to sell me their VoIP and I always say, "it doesn't matter what VoIP provider I use, it's still your internet connection that's the problem." I'm starting to realize now that maybe it DOES matter what VoIP provider I use. Comcast Digital Voice = packets get through, Vonage = packets get dropped?
The power goes out? No power to the modem, no VoIP. Or how about when the tech puts a trap on your phone because he thinks you're pirating cable? (Happened about 5 times to a friend of mine with business class cable internet). Or how well does it work when the cable company screws up, and burns out a bunch of modems with a too strong signal (happened to many people around here). Or what happens when the weather gets exceptionally hot, or exceptionally cold and wreaks havoc with the S/N ratio of the lines?
The phone lines were engineered to be very reliable. In my experience cable has been something that's been less than reliable (because no one dies if the cable goes out).
AccountKiller
Cable providers also led the way in audio quality
What we all REALLY want to know is how well does it handle our Dial-Up connections?
"Everything you know is wrong. (And stupid.)"
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I just got VoIP two months ago through my "local" cable company, and the voice quality has been excellent. And, the bill was even better! So far, so good.
An interesting side not if you're a Verizon phone and DSL customer. Simply mention the fact that you're dropping DSL for cable and they first try and scare you by saying you are on a shared network and will certainly be targeted by intruders. If you can put up with their speach, then they'll offer at least one free month, and in my case, $10 less per month to stay with their DSL.
Then, finally, the second call to cancel phone service they give a speech about unreliable 911 service and dropped calls with VoIP. If you can patiently wait for that speech to conclude, they'll offer another discount to keep you as a land-line customer. In my case, it was $10 again! No rebates on long-distance though...
Bottom line, call up your phone company now, and say you want to cancel DSL and/or land-line service. You will certainly get a free month and a monthly discount.
I lived in 3 different towns in NJ and one in CA and I think the landline has gone down like once in 25+ years. I've never had a landline to landline call dropped, ever. I didn't even think that was possible.
I have had the cable drop off dozens of times though as have most people I know. I'd rely on Verizon for VOIP in a second but I would trust Cablevision to deliver my email. If what they are saying is actually true on a national scale then I'm shocked.
If you wanna get rich, you know that payback is a bitch
Cable providers also led the way in audio quality; the top firm in Keynote's study actually turned in an MOS of 4.24, above most real phone networks.
If I recall the DOCSYS standard correctly (that's the one for cable settop boxes), the framing provides the phone company TDM-style 8 kHz synchronized clock, and the phone signals are carried as full-rate uncompressed bytes.
In other words, POTS-over-cable is a 64 kbps synchronized digital signal, identical to what's carried on the phone companies' own ISDN, T, and SONET carriers, and is switched onmodified on and off the rest of the digital network unmodified. The A-D conversion happens in the settop box. It's like having your POTS phone at the switching center within wire-feet of the multiplexer. (The clocking is also good enough to encode analog signals from FAX and 56K computer modems. It has to be, as a side-effect of the need to time the upstream packets properly.)
POTS, on the other hand, is A-D converted at a central office or a "remote terminal" (in a box at the curb) and carried the rest of the way - blocks to miles - in one of a bundle of wires. This is subject to crosstalk, distortion (selective delay and attenuation of higher frequencies), and a number of other pathologies that lower the signal quality.
So it is not at ALL surprising that cable POTS signal quality beats telco POTS. Cable's signal is about as pristine as you can get.
(And VoIP isn't in the same ballpark, due to both compression and timing uncertainties.)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
My wife's sister has Vonage. Every time she calls I can't hardly hear a word she's saying.
I love Vonage.
(Which goes to show how long ago I was looking into it. B-) )
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Something to consider:
1. How does keynote benefit?
Keynote's VoIP Competitive Monitoring Solution addresses the need of marketing and operations executives to understand their performance relative to competitors, and to gauge the impact on the end-user experience of both their infrastructure investments in new markets and their enhancements to services in existing markets.
They have a pretty big incentive to excite some potential customers.
2. What was the methodology?
Keynote placed local and long distance VoIP calls to destination phone numbers on a standard (PSTN) phone service. Calls were placed from San Francisco and New York once every 30 minutes on every VoIP provider and network carrier combination. A total of 125,000 calls were placed over a month-long period. Calls placed using competing VoIP services were compared to traditional phone "toll quality" standards to determine what residential customers can expect when switching from traditional phone lines to VoIP.
Who is -every- VOIP provider?
My personal experience with VOIP over cable was definitely worse service than POTS for the same price as POTS. Where's the value the cableco was supposed to be providing?
http://www.maxineudall.com/2010/02/should-economists-be-sued-for-malpractice.html
...meaning that the service was more often available and connected calls without dropping them.
But... How often do you drop calls on a PSTN? Hello?? Hello??? Can you hear me now????
After countless fees charged over the years (not directly related to the service rendered,) not a penny of that has been used to improve those ancient phone lines but instead used to line the pockets of telecomm executives. It could be argued that they're used to improve lines, just so happen to be the bottomline of executives and not phone lines...
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Teamspeak, Ventrillo
Granted, this isn't really a phone replacement, but if all the people I want to talk to are on their computers anyways, then it works great.
There is no mod option "-1: Disagree" for a reason. "Overrated" is not an acceptable substitute. Post something instead.
Back to the phones: I have asked telephone techs and cable techs. The telephone system can run off their battery banks for a week or so, the cable guys say 2 days tops. The cable company here offers two telephony services: CableTelephone, or VoIP telephone over their high-speed cable service. The VoIP option is half the price.
If there is one thiing I dislike about VoIP calls it is the lag time. It seems that when I am on a conference call, it is hard to jump into a conversation because when you wait for the right time to jump in and start talking, someone else also decided to talk at the exact same time, but you only learn about it a bit later and talk over whoever else jumped ahead of you. It really makes you look like an asshole.
VoIP service: Cox Cable
i have -never- had an analog phone line not connect me or drop calls. how can something be better than 100%?
Our experience is that it matters very much what VoIP client you use. We've compared just about any VoIP client and, with all other parameters being the same, keep getting the best results by far with Ekiga, even without optimizing the voice codec.
I am a happy customer with Sunrocket, Internet VoIP Service (sunrocket.com) for almost 2 years now. I am in Oregon, USA so I am on comcast network and never being happier with my phone service. Big fat telco QWest bills were like $55 per month with Sunrocket only $199 per year ($17 per month) and all phone features you can imagine with all-you-can-eat US/Can/Mex plan. No contract. No installtion. No cancellation. No sh*t. Screw the big fat QWest with their customer "milking" fees and shmees. Sunrocket is like a "google" of the VoIP services.
steve
Oh, you're not stuck, you're just unable to let go of the onion rings.
Does this happen to anyone else?
Cheers,
Bill
bamph
Verizon is replacing all of their copper landlines with FiberOptic cable. Signal loss is almost nill delay to the CO is almost nill. I'd like to see cable signals beat the speed of light! Cable is a shared connection, yes sometimes your speed is great, but sometimes its junk. I had adelphia cable internet, VOIP, and TV for a year, I dropped it in favor of nothing the quality was so bad.
The problem isn't with bandwidth. Anytime you place a call on a land line (non-local), your signal on the analog POTS line is digited (8KHz, ADPCM, uLaw encoded) at the FXO (foreign exchange office) and transfered over a channel on a T1. 8KHz is plenty of bandwidth to transfer the human voice (Bell labs figured this out in the 50's)... With VOIP, extra bandwidth on one end doesn't give you a thing if you're calling a non-VOIP phone on the other end... eventually the signal gets transfered over a T1, at 8KHz (the lowest common denominator). The real problem is that VOIP is packet switched, without a guarantee of delivery... and as you know with IP, you can also run into issues of packets being received out of order. The real value in VOIP isn't QoS (it won't be for years to come)... the real value is in being able to deploy voice services over an existing IP infrastructure... no more clunky and expensive PBX's!
Now, if you're placing a VOIP to VOIP call (I assume this is what the test was... didn't read TFA), there is no 8KHz constraint and throughtput can theoretically be higher.
# man tar
I'm not sure how they come up with the reliablility comparisons. Wouldn't all phone systems depend on each other? If I called your VoIP # from my land line and it wouldn't go through, how would I know who is to blame? Seems to me like I would have to ask one of the companys. Of course I'm sure they would tell me the truth. Also if one company services 10,000 calls a day and the other 10 billion is there success rate comparable? (not saying those are the #'s I have no idea but I'm sure there are far fewer VoIP calls) I wouldn't think so. Anyone whos used VoIP of any kind will tell you it has many advantages but reliablity is not one of them, the second you plug your modem or VoIP phone into the power outlet you should realizes that.
I use Asterisk with pots, and voip at work on a dsl connection and at home on cable, and it works nicely. Thats the good part.
At home, I watch the commercials for Charter voip, and just roll over laughing. While my sytems at home and work are all on UPS systems, and will hold for at least 6 hours, Charter doesnt. If the power is out, so is the cable.
Every time it rains a quarter of in inch, the cable goes down, this is even after they have came out and fixed lines, replace amps etc.
Until the cable company can show me they can keep their system up during storms etc. We will keep our land line.
WAHHHOOO! Finally, a way to screw the greedy phone companies. I have Vonage over cable here in Mexico and I couldn't be happier with the service and quality. This is the way to go. Death to the phone companies. Now, if someone can just figure out a way around stupid "standard banking practices" my life will be complete! :)
My VoIP bill so far has been about $5 for 16 months of service - after I dropped the scumbags at Vonage with their $10 disconnection fee.
So in May 2005, I pre-paid $10 for a teliax account that I use for the type of calls that would eat into my included cell airtime - calls to 800 customer service numbers which involve long wait times. I still have about $5 left, even though I've made quite a few calls.
I also make many long international calls using voiptalk. Excellent sound quality, barely appreciable lag, $nothing/minute, $nothing/month, $nothing/ever.
I've lowered my conventional-telco costs down to $6/month - the fee Qwest extorts for my Speakeasy naked DSL circuit. I look forward to dropping that to zero when fixed wireless becomes feasible.
Cellphone service is next.
"while 'traditional' VoIP call quality lagged behind landlines, service from cable ISPs was much better because of their use of PacketCable: 'VoIP from the cable companies actually surpassed the traditional phone network in reliability, meaning that the service was more often available and connected calls without dropping them."
Isn't that common sense, and the reason why we need net neutrality?! If companies like Comcast would stop crippling their competitor's VoIP service (read: Vonage), then perhaps this little study would have found different results, namely that VoIP in general can sound better than landlines regardless of the operator. Case in point, Vonage to Vonage calls with max voice quality settings (in the router) are great, or I should say they WERE great until Comcast started messing with people's packets about a year and a half ago.
"On a scale from 1 to 10, people are stupid"
The first time I connected on Skype (from Shaw in Manitoba to Telus in Alberta), the voice quality was amazing. My father instantly noted that I sounded like I was "right there". Just like watching HD for the first time, other phones (especially mobiles) sound so much worse since we've started runing Skype.
How nice for you. So am I, but only because my internet is DSL. Almost every time there is a power failure at my house (in a small town, 2000 people) the cable goes out. I have to assume that that means that my phone service would be down as well.
Fortunately, my landline phone has not failed since I moved into my house. In fact, I can recall only one time in my entire life that the phone service went out, but if I had a nickel for every time the cable went out (even without a power failure!) I'd be Bill Gates.
My amazing wife - Artist, Author, Philosopher - Laurie M
... "VoIP with bandwidth to spare, controlled low latency, and QoS is sometimes almost as good as a dedicated voice network"?
Gee, any telco engineer or high-level tech could have told you that...
Disclaimer: I've been one. From a purely technical POV, VoIP is something of a con. It's attractive to end-users because it offers a chance to break free from the telcos. It's attractive to telcos because it allows them to homogenise their networks onto a single IP-based platform. Technically, though, it's a shitload of kludges to shoehorn something into a transmission platform that was never designed for the requirements of that kind of traffic. Underneath those kludges it's unreliable, inconsistent, and doesn't scale terribly well - though, because it's based on commodity technology, it's relatively cheap to implement/expand.
What part of "a well regulated militia" do you not understand?
Yah it's surprising. Every time someone tries to call me using some cheap-ass VOIP alternative, the sound quality is horrid. Often also have lags, where someone says something and there's a 2 second delay before they hear you... Makes for difficult conversations.
Good point. And, we've made something as easy as making a land-line call potentially so complex that the average person can't even do it. For some reason I'm always having to do ridiculous things like unplugging my cable modem, router, and disconnecting the coax from the modem (in some special order that is hard to reproduce) in order to "fix" my internet connection. If I had Vonage for voice on top of all this it would be a real train wreck.
The problem is, people have learned to accept that "the internet is down", but it would be a much bigger deal if the water was off, the electric was out, or the land line was down.
Wouldn't happen. Cable ISPs are mostly buying large pipes - the main question is whether they buy them big enough. The big problem is that the DSL access companies are very likely to *not* QoS the packets unless their customers pay extra, so VOIP will get swamped by your BitTorrent traffic, or music downloads, or similar high-volume data traffic. The cablecos also need to manage outbound traffic appropriately, but that's not too hard, even though they're almost certainly running 80kbps voice (64kbps raw + RTP/UDP/IP headers) rather than compressed.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Eventually it degraded to the point that the audio sounded like "KKKKXKXKKXKXXXXKXXXKKXKXKX", at which point the replaced the dropline that was rubbing against a tree branch, and then it did 2400 baud just fine again. On the other hand, if it's just a lame handset, it's just a lame handset.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Many of the VOIP services are designed to use the 8kbps or 5.6kbps codecs instead of 64kbps (expands to about 24kbps after RTP/UDP/IP overhead.) Mobile Phones have taught the technology market that phone transmission doesn't have to be that great as long as you've got a decent handset and there aren't trucks driving by while you're talking.
Some of the early cable voice standards weren't VOIP - they were 4KHz analog channels carved off the bottom of the transmission spectrum, connected to standard phone switches.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
The economics of cable modems are that you're piggybacking service on top of Cable TV service, and the reliability numbers are driven by how many technicians with trucks they hire to go fix things when they break, plus how often installers break things by accident. For telephones, that's high reliability, with lots of techs and trucks, because there's not only a century of hype and propaganda about highly reliable service service, but it's a regulated industry that really gets on their back for slow repair times because "people might die" if you don't fix their phone fast. For Cable TV, on the other hand, it's just television, and if it's not working you can read a book or watch DVDs." That clashed rather rudely with the Internet customers' expectations about 100% uptime, short downtimes, and major panic if things stay broken all weekend when a snowstorm takes out their service on a Friday night.
Also, cable TV networks were built on a town-by-town bases, with decisions usually made about how many free channels the town council could use and whose brother-in-law got the street-repair contracks, not about who had insightful vision into the future of telecommunications. So there was a lot of random equipment, often low-quality or in bad shape, running cable TV - the cable modem business has forced them to upgrade it a lot, and incresaing node density means that fewer users lose service if something fails.
I'm not sure whether my own cable TV service has been more reliable than my phones or DSL or not. Every couple of years a phone installer messes up something while working on a box down the street and I lose service for up to a day and a half before they fix it, and it takes down my DSL as well as my voice service (so I just use cellphones.) My cable TV service problems have tended to be that an individual channel stops working for a few days, or sometimes the whole thing runs black, but the main problem was lousy gradually-degrading video that took over a year to fix.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Also, the quality of other VOIP providers is probably based on their internet connection. Ironically, the people with cable internet connections probably have some of the worst results using other providers since my experience with cable internet has been downtime and packet loss. It was very fast and had low ping times for the most part when it was up, but there was still packet loss. It was never as fast or reliable as my 5mbit DSL from QWest/NetINS has been.
Having spent a fair bit of time working with automated test equipment to characterize voice quality in a compressed VoIP environment, I must say that the results are too poorly documented in the article to be meaningful.
//lt//
1. MOS may only be projected by automatic tests. It is a measure of how happy a user is with the quality and actually requires someone to sit there and listen to a call.
2. PESQ, JMOS and other machine scores project the quality (and sometimes MOS) using voice-range tones and measuring the quality against models that they believe reflect user experience. The reality is that these tests are only valuable within a broad range since experience shows that users are not sensitive to broad range tone capacity unless they use one of those clicking languages you see on the Discovery Channel.
3. PCM is the gold standard for voice. Uncompressed and sampled properly the maximum acheivable MOS score is estimated around 4.4. This is the famed technolgy behind digital switching and it is rarely encumbered by "poor clicking" as some users have noted. DDS approach to clock synthesis is far beyond such low levels and because of the pesiochronous nature of most digital voice transmission should be sufficient.
4. Many VoIP and all GSM carriers utilize compressed voice. Compressed voice tends to degrade the quality of a call slightly. Acceptable MOS scores in this condition are often 3.0 to 3.8, while PCM can typically achieve 3.5 to 4.4. Although compressed voice receives a bad rap from many people, the reality is that it continually improves as DSP technology evolves and it no longer is overwhelmed by the problems early users in neighborhoods with carrier loop extension through DLC gateways suffered through.
I have long provided compressed and uncompressed service to customers. As a discerning audiophile, I never felt as if I was shortchanging someone by introducing a variety of technologies. Any well-designed network will perform more than adequately and achieve user satisfaction. The main reason users don't experience satisfaction is that most of the telecom industry is made up of twits unable to engineer their ways out of a paper bag.
If Comcast quality is better than other providers, I ascribe that to an effective consultant or architect and give kudos to them and not some kludgy PacketCable standard.
Not surprising with any broadband VoIP. People remarked from day one that my quality with Skype on mediocre DSL was superior to my landline desk phone.