Nearly 20 percent of Internet telephone test calls experienced unacceptable call quality over the last 18 months, according to data collected from TestYourVoIP.com, a free, voice quality testing portal that enables consumers to independently measure the quality of their broadband Internet phone connections.
From late 2004 through mid-2006, the test results generated by Test YourVoIP.com showed a consistent decrease in overall voice quality as calculated via 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).
Test calls with a MOS of 3.6 or better are typically regarded as having satisfactory quality. The number of test calls throughout this time that achieved a MOS of 3.6 or higher, also known as Acceptable Call Quality (ACQ), was only 81 percent.
Over the last few years, the global market for consumer VoIP services has grown to nearly 20 million subscribers and that does not account for the millions of other users that use free software like Skype or IM-based applications like MSN.