Test & Measurement

Study: VOIP Quality Getting Worse

A recent study has found the quality of VOIP calls declining steadily over the past two years, and points to network congestion and lack of service prioritization as the culprits. (See VOIP Quality Dropping.)

Brix Networks Inc. has come up with a clever way to study the quality of VOIP calls -- a portal called TestYourVOIP.com where consumers themselves place dummy calls. Brix says the site has generated nearly a million test calls since it launched in March 2004. (See Report Hisses at VOIP Quality.) Brix says almost 20 percent of those calls rated “unacceptable” against a long-used quality testing algorithm called the “E Model.”

“It’s pointing to congestion and competition with other media,” Brix CTO Kaynam Hedayat says of the study’s implications. “There’s no differentiation in the network between VOIP and other kinds of traffic like video or gaming -- it’s just pure democracy.”

The test calculates a Mean Opinion Score (MOS), a common objective measure of conversational voice quality that rates calls on a scale from one (bad) to five (excellent) based on such things as jitter, packet loss and latency. (See Keynote Monitors VOIP and Who Makes What: Test & Measurement Gear for Next-Generation Networks.)

Test calls with a MOS of 3.6 or better, Brix says, are typically regarded as having satisfactory quality. Only 81 percent of the test calls achieved the 3.6 threshold.

Some in the VOIP business feel such studies show that VOIP providers are victims of their own success. “You’re dealing with consumer expectations as much as you are changes in call quality,” says SunRocket Inc. spokesman Brian Lustig. “Consumer expectations of land-line service are very high, and as more consumers begin to feel comfortable with VOIP, expectations rise.” (See VOIP Testing Goes Live.)

Lustig disagrees that overall VOIP quality is on the decline. “There’s been an explosion of VOIP use in the last couple years, and part of the reason for that is VOIP quality has improved,” Lustig says. Indeed, the global market for consumer VOIP has grown to nearly 20 million subscribers, researchers say.

Lustig says call quality improvement is one of the main things driving VOIP providers toward forming peering arrangements with one another. (See VoicePulse Peers With XConnect.) VOIP providers can avoid the “uncertainty” of the PSTN by forming direct IP handshakes with other VOIP providers, Lustig says.

Global IP Sound AB CEO Gary Hermansen points out that when a voice call leaves the IP domain for the PSTN, it must be transcoded into a lower-quality sound stream. He says quality is further challenged by the fact that VOIP services are now used by millions of people, and by the fact that video packets have been added to the service in many cases. (See Skype Uses Logitech, On2.)

TestYourVOIP.com displays a real-time “weather map” of the Internet's current ability to support real-time services, such as VOIP and IPTV. Registration is required to use the site.

Brix’s interest in the subject stems from its own product line -- real-time VOIP and IPTV testing and monitoring gear. Brix is one of a growing number of companies marketing the technology; others include:

(See Who Makes What: VOIP Infrastructure Equipment, VOIP Testing Goes Live, VOIP Testing: The Startup Mentality, and Empirix Upgrades VOIP Tracker.)

— Mark Sullivan, Reporter, Light Reading

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OldPOTS 12/5/2012 | 3:46:38 AM
re: Study: VOIP Quality Getting Worse Is there any breakout of VOIP Quality by vendor. I ask this not only to see who has good quality, but what is considered VOIP service- method of delivery.

Mark Sebastyn 12/5/2012 | 3:46:36 AM
re: Study: VOIP Quality Getting Worse This report has been ricocheting around the net for a week or two.

Doesn't it strike anyone that there might be a conflict of interest here.

Brix, a company that sells equipment to monitor VoIP and other application quality on the net, reports that there are degrading quality problems in VoIP calls?

What if they reported - there are no quality problems? Then no one would need their box!
Michael Harris 12/5/2012 | 3:46:33 AM
re: Study: VOIP Quality Getting Worse A clever marketing maneuver indeed, encouraging VoIP users to benchmark their own call quality, and then using that as amunition to try to pull through business from service providers.

As you point out, by definition, this is not an independent, unbiased testing program. That said, are findings of VoIP call quality degradation on the public Internet really so surprising?
voyce_overipee1 12/5/2012 | 3:46:31 AM
re: Study: VOIP Quality Getting Worse So I just ran some tests and capture the packets to see what was going on. It's cool cause they are actually using SIP to make these test calls, using 20ms g711 uLaw, with RTCP. And they really do make the call from your PC to a brix box in the city they claim to, except Helsinki looks like a UK address to me, but close enough.

The problem is that's only testing it as if the call was made direct, and the voip provider is someone without a network. For those of us who own the network, we can provide qos for the media, but you won't get it using your own java sip client as this brix test does. This brix call doesn't even mark the packets for diffserv, not that we would accept their marking it anyway. This brix thing might as well have just sent anything over UDP over the Internet and measured the "performance". No one expects it to do any better than skype that way. Sometimes its good, sometimes it ain't. If it gets worse over time that's good for me.

Michael Harris 12/5/2012 | 3:46:29 AM
re: Study: VOIP Quality Getting Worse Came to the same conclusion. See http://www.lightreading.com/bl...
OldPOTS 12/5/2012 | 3:46:27 AM
re: Study: VOIP Quality Getting Worse RE: "For those of us who own the network, we can provide qos for the media, but you won't get it using your own java sip client as this brix test does."

Does that QOS not mean the loss of 'Net Neutrality' in those networks?

Then I got this interesting piece from a friend when he viewed the article:

"These events generate additional pressure to re-regulate Telcos.
And where will the pressure come from? The non-regulated service providers. When they have to provide traditional telco service levels -- which will be driven by customers and newly awakened regulatory agencies -- there will be a demand to be protected from (nasty old) competition.

The new service providers will decide that rates need to be set high enough to provide the required services by the regulatory agencies for the good of the consumer. (Bend over, consumer.)

paolo.franzoi 12/5/2012 | 3:46:23 AM
re: Study: VOIP Quality Getting Worse

That is the argument that most people make. That having reserved bandwidth as a telco means that my non-reserved bandwidth can not get access to that bandwidth in an oversubscribed network. It becomes a inherent choking of Internet bandwidth to service the walled garden services.

So, in this case the VoIP service of say AT&T (as a walled garden) gets high QoS and always works wonderfully. The VoIP service of Vonage gets Internet QoS and does not always work wonderfully.

The RBOC counter to this would be to be able to sell these QoS services in a wholesale manner to other suppliers. If this wholesale could be assured to be structurally separate, then that would give everybody a chance to offer the same kind of services with the same cost structure for the access and metro.

Michael Harris 12/5/2012 | 3:46:23 AM
re: Study: VOIP Quality Getting Worse Does that QOS not mean the loss of 'Net Neutrality' in those networks?

Depends on how you define "Net Neutrality."

The argument that application prioritization automatically violates Net Neutrality principles is brain-dead.

Maybe Congress should step in with regulations to ensure the US Postal service can only offer one class of mail delivery. Parcel post for eveyone. No Priority Mail or -- heaven help us -- Express Mail overnight delivery. It's just plain unfair that some letters arrive faster than others!

paolo.franzoi 12/5/2012 | 3:46:21 AM
re: Study: VOIP Quality Getting Worse
I understand your comment, however....

The reason to set the deal with the application provider is that at that point a VPN connection can be set to that application provider. Thus, theoretically QoS can be managed from the consumer all the way to the application.

The consumer oriented version does not have that capability. You get the QoS through your Broadband Access Supplier to the Internet, where QoS is lost.

The former case provides likely less services but better guarantees than the latter case.

Michael Harris 12/5/2012 | 3:46:21 AM
re: Study: VOIP Quality Getting Worse That is the common concern about the argument that most people make. :)

My preference is to see broadband providers directly offer consumers the option to purchase QoS for any application, rather than users being subject only to the deals the carrier makes.

Zealots that argue any QoS is evil seem more interested in net neutering than net neutrality, per se.

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