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August 28, 2006

Minacom Study Reveals the VoIP Call Quality on Steady Increase

By Susan J. Campbell, TMCnet Contributing Editor

For those organizations considering a VoIP implementation, but concerned about the degradation in quality of the call, a new study released by Minacom reveals that VoIP phone service actually sounds better and connects faster than the standard public-switched phones network (PSTN).
An Internet Phone quality study was completed recently by Brix Networks, and covered by TMCnet, that indicated that 1 in 5 VoIP calls were classified as unacceptable and that call quality was steadily decreasing. Results like these can be extremely detrimental to the adoption of VoIP throughout multiple industries.
However, this study evaluated computer-to-computer (PC-PC) Internet phone service, similar to those offered by Skype, Google Talk, MSN and Yahoo Messenger. Minacom felt is was important to highlight that the quality and service reliability of these applications does not compare to that of the VoIP phone services offered by telcos, cable operators and broadband VoIP providers.
Minacom spent the last 12 months collecting data using their standards-based, single-ended service quality test system. Results indicate that VoIP service quality increased steadily over the past year, with an average Mean Opinion Score (MOS) of 4.2, compared to 3.9 for the PSTN, based on a range of 1 (worst) to 5 (best).
Based on a MOS threshold of 3.6, only 1 out of 50 calls in North America were considered to be unacceptable. Worldwide, the result was 1 out of 10. Over the same period, greater than 85 percent of VoIP calls exceeded average PSTN quality and improved in all regions.
Connections speeds for VoIP proved faster than those for PSTN. On average, the VoIP calls connected at 8.2 seconds, compared to 8.9 seconds for those placed over the PSTN. Calls placed to North America proved to connect faster on the PSTN (4.3 seconds versus 5.7 for VoIP), while international calls connected faster with VoIP (8.7 seconds versus 10.4 for PSTN). Results indicate that VoIP is closing the gap, however, as it connected 2 seconds faster in July 2006 than a year earlier.
To complete its testing, Minacom completed calls over PSTN, managed broadband and cable VoIP lines, the same services offered to residential and enterprise customers by phone, cable and hosted VoIP providers. Minacom’s PowerProbe 6000 service level test probe placed hundreds of calls each month from the company’s QoS labs in Montreal, Canada to public destinations around the world over PSTN, broadband VoIP, cable VoIP, DSL, FTTP and wireless networks.
The results were published in the Minacom QoS Benchmark Report. These reports are used by the ITU Quality of Service Development Group in studies summarizing global phone quality, published annually to carrier around the world for the consistency and accuracy of the measurements reported.
Because speech quality evaluation must consider analog signal analysis, Minacom’s DirectQuality R7 test systems uses a combination of ITU and industry standard algorithms to calculate listening quality MOS using both analog and IP measurements. MOS scores based only on IP packet statistics do not capture the effects of echo cancellers in network equipment and telephone adapters, noise introduced by copper wiring or issues with call volume and delay.
The PowerProbe 6000 IVR Test Agent measures a wide range of analog and IP impairments, such as noise, echo, delay, packet loss, call volume, jitter and loss, in addition to a complete array of connectivity metrics including Post Dial Delay (PDD), Answer Seizure Ratio (ASR) and Dial-Tone Delay (DTD).
When discussing MOS scoring, Frost and Sullivan Telecom Industry Manager & Analyst, Jessy Cavazos, commented that carriers are becoming increasingly educated about MOS and want to know where the scores are coming from. With numerous products in the market that only look at packet metrics, many carriers are starting to see degradation they should not see or not seeing it where they should. As a result, Minacom uses three different technology sources for MOS scoring instead of only one in order to capture all possible service issues with the highest degree of accuracy available.
According to Michel Nadeau, President and CEO of Minacom, VoIP has undergone rapid deployment over the past few years as service providers become more confident that the technology can deliver PSTN-quality service. Minacom’s test results confirm that VoIP services available today can equal or exceed the quality of traditional PSTN offerings. VoIP, delivered digitally end-to-end, can outperform the PSTN and with the introduction of wideband codecs and the ever-faster Internet backbone, VoIP calls will soon be the next best thing to ‘being there’.
Scott Sumner, Marketing Director for Minacom contributed that, “this study shows the steady progress VoIP is making as a viable replacement communications technology for traditional public-switched wireline service, results that are a testament to VoIP equipment manufacturers and service providers, and the Internet Telephony community as a whole. With IP peering fabrics starting to replace PSTN links between VoIP provider networks, all digital, end-to-end pure VoIP calls will become more common, further increasing call quality while allowing advanced calling features that are currently limited by PSTN gateways. As VoIP continues to evolve, it will take its rightful place as a critical communications technology – high quality, low cost and widely accessible worldwide.”
VoIP offers businesses and residential consumers alike the benefit of utilizing the Internet for low cost communications. If call quality was truly on a steady decline for all VoIP calls, this option would no longer remain viable for the majority of the market.
And, while it is true that the Internet is congested, these results from Minacom indicate that any increases in the congestion are not negatively impacting VoIP. Instead, connection time and quality has proven to increase in the past year. If services continue to progress in this manner, it is very likely that VoIP will become the standard, creating substantial demand throughout the world.

Susan J. Campbell is a contributing editor for TMC and has also written for To see more of her articles, please visit Susan J. Campbell’s columnist page.

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