Voice over Internet Protocol (VoIP) call quality is going down the
tubes, or so says a recent study by Brix Networks, which found that
one out of every five VoIP calls is of unacceptable quality.
"It was a real head snap," said John Burnham, Brix Networks'
marketing vice president. "It really did surprise us."
Brix has been asking VoIP users -- residential, business and
consumers -- to test their call quality free of charge at the
TestYourVoIP.com voice quality testing portal.
Since March 2004, more than 1 million VoIP users tested their
systems' call quality through the portal. Of those 1 million calls,
about 20% were considered low quality and therefore unacceptable.
Around the same time last year, only about 15% of VoIP calls were
considered to be of unacceptable quality, according to Kaynam
Hedayat, Brix Networks' CTO.
Brix tested VoIP call quality by calculating a Mean Opinion
Score (MOS) that rates calls on a scale of one to five, with five
being bad and one being excellent. Calls with a MOS of 3.6 or
better are typically regarded as having satisfactory quality.
Overall, only about 81% of calls tested achieved a MOS of 3.6 or
better, which Brix dubbed Acceptable Call Quality (ACQ).
In 2005, roughly 82% of calls tested had acceptable quality;
that slipped to 80% in the first half of 2006.
One theory for the slide in overall call quality is the
complexity of applications being run over the Internet and IP
networks, Hedayat said. Adding in video and a host of other
downloadable applications slows down voice packets, resulting in
call degradation.
Hedayat said that VoIP service providers now must focus more
closely on why quality is slipping.
"For long-term sustainability, providers of [VoIP] will need to
concentrate on the root causes of call quality degradation,
including late packet discards, lost packets and round-trip voice
latency," he said.
Brix's testing site, TestYourVoIP.com, uses both hardware and
software to test and monitor IP service and application quality. To
use the testing, users download a small applet that initiates a
test phone call using the SIP call-signaling protocol. Then,
appliance-based Brix Verifiers -- in Boston, Helsinki, London,
Montreal, San Jose, Sydney and Vienna -- answer the test calls to
measure the call quality.
Along with maintaining the testing sites, Brix Networks makes
VoIP monitoring products for enterprises and service providers.
Zeus Kerravala, a vice president at Boston-based The Yankee
Group, said most enterprise users need not worry about call quality
degradation because many companies run VoIP over their own
networks. Call quality could plummet, however, for companies using
hosted services or services where the hosting company doesn't own
the network.
"I think there's a lot of truth to that," Kerravala said of the
overall slide in call quality. Most users run some sort of instant
messaging service, file sharing software and video, while also
using voice. That can destroy call quality and introduce latency
and jitter.
"People are using the network for more things," he said, later
adding that "this is going to become a bigger issue" as more
services are piled onto the network.
Kerravala said that while adding bandwidth is one solution,
carriers may also want to start charging more to prioritise voice
traffic in order to ensure quality.
"The reason it's a problem now is because nothing's
prioritised," he said. "But no one's really trying to address that
yet."
This article originally appeared on
SearchVoIP.com.