According to a testing company, Minacom, VoIP phone service worldwide "now sounds better and connects faster than the standard public-switched phone network (PSTN).". More specifically according to this report that data collected over the last 12 months by its standards-based, single-ended service quality test system show that the quality of VoIP services offered by telcos, cable operators, and broadband VoIP providers has increased steadily over the past year, with an average Mean Opinion Score (MOS) of 4.2, compared to 3.9 for the PSTN. MOS, an International Telecommunication Union standard, is commonly used to describe speech quality. It ranges from 1 (worst) to 5 (best).
Minacom says that "Based on a MOS threshold of 3.6, only one out of 50 calls in North America were considered to be unacceptable - one in 10 worldwide - while greater than 85 percent of VoIP calls exceeded average PSTN quality over the same period."
Minacom refuted the results of recent Internet phone quality study by rival testing organistion Brix Networks which it says found that 1 in 5 calls were unacceptable, and that call quality was steadily declining.
According to Minacom, the Brix report "evaluated computer-to-computer (PC-PC) Internet phone service, similar to those offered by Skype, Google Talk, MSN and Yahoo Messenger...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.