According to a new analysis from Canadian service level test house Minacom voice over IP (VoIP) phone service now sounds better and connects faster than the standard public switched phone network (PSTN). According to data collected over the last 12 months by Minacom's standards-based, single-ended service quality test system, VoIP service quality increased steadily, with an average Mean Opinion Score (MOS) of 4.2, compared to 3.9 for the PSTN (MOS is a scale commonly used to describe speech quality, ranging from 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 - 1 in 10 worldwide - while greater than 85% of VoIP calls exceeded average PSTN quality over the same period. Detailed results apparently show that VoIP service bettered PSTN quality worldwide, and improved in all regions over the course of the survey. In addition to superior sound quality, calls over VoIP connected quicker overall - 8.2 seconds on average, compared to 8.9 seconds for those placed over the PSTN. Regionally, the PSTN was faster to connect for calls placed to North America (4.3 seconds versus 5.7 for VoIP), while international calls connected faster with VoIP (8.7 versus 10.4 seconds for PSTN). Linear regression indicates that VoIP is closing the gap, connecting 2 seconds faster in July 2006 than a year earlier.

The Minacom findings contradict those of the recent Internet phone quality study by Brix Networks that suggested that 1 in 5 calls were unacceptable, and that call quality was steadily declining (click). Minacom felt itself duty bound to clarify, for both those in the VoIP industry and individuals and enterprises considering VoIP service, that the Brix report evaluated computer-to-computer (PC-to-PC) Internet phone services, similar to those offered by Skype, Google Talk, MSN and Yahoo! Messenger. Minacom says 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 who carefully deploy, monitor and manage the quality of their services. It adds that PC-to-PC VoIP quality is subject to many diverse impairments, including firewall settings, computer performance, antivirus installations, high-compression codecs, and Internet bandwidth shared with gaming, file downloads, web surfing and email. By contrast, VoIP offered by service providers is switched using telecom grade equipment, uses lower-compression codecs, and is prioritised over regular Internet traffic using sophisticated, standards-based multimedia telephone adapters (MTAs), maintained and monitored by the operator.

Minacom’s own tests were conducted over PSTN, managed broadband and cable VoIP lines, the same services offered to residential and enterprise customers by phone, cable and hosted VoIP providers.

“Carriers are becoming increasingly educated about MOS scoring and want to know where MOS scores are coming from,” comments Frost and Sullivan Telecom Industry manager and analyst Jessy Cavazos, adding, “There are numerous products in the market that only look at the packet metrics. Hence, many carriers are starting to see degradation they should not see, or not seeing degradation they should see. False service quality alarms result in unproductive troubleshooting efforts by service providers, whereas unidentified quality issues ultimately leads to dissatisfied customers. That is why Minacom uses three different technology sources for MOS scoring instead of only one, so as to capture all possible service issues with the highest degree of accuracy available.”

“Over the last few years, VoIP has undergone rapid deployment as service providers become more confident that the technology can delivery PSTN-quality service. Our test results confirm that VoIP services available today can equal or exceed the quality of traditional PSTN offerings. Wireline copper telephony is subject to long, aging wiring to residences, quantisation distortion introduced by narrowband PCM codecs, and least-cost routeing decisions which can result in quality issues,” contends Michel Nadeau, Minacom president and ceo. “It is no surprise that VoIP, delivered digitally from end-to-end, can outperform the PSTN; with the introduction of wideband codecs and the ever-faster Internet backbone, we should expect that VoIP calls will soon be the next best thing to ‘being there’. Well-planned day-of-install testing and monitoring strategies consistently lead to high-quality service, and a unified network for voice and data.”
John Williamson