VoIP still suffering from audio delay

VoIP services providers are still experiencing significant problems with audio delay in their calls, according to a study by Keynote Systems. And while the call quality of VoIP and PacketCable have continued to improve, both services still lag behind PSTN (Public Switched Telephone Network). The study used indicators such as service availability, call completion percentage and audio delay to test 12 different VoIP and PacketCable (IP telephony over cable) phone services for their reliability, responsiveness and clarity.

The study then compared the VoIP and PacketCable indicators with those of PSTN services from AT&T and Verizon. Unlike previous studies, the latest only looked at VoIP hard phone services, which rely on actual telephones, and not the soft phone services, which are generally performed through computers. "Our key finding here is that there has been significant improvement for VoIP services, but there is still a difference in terms of quality of calls," says Rajeev Kutty, VoIP product manager at Keynote.

The study found that VoIP service providers are still experiencing significant problems with audio delay in their calls. While both PSTN and PacketCable both measured a mean average audio delay of below 150 milliseconds, VoIP providers measure a one-way audio delay of between 150 to 250 ms. The best mean audio delay for a VoIP provider came in at 149 ms, while the worst came in at 279 ms. Even so, this was far better than the worst delay recorded in Keynote's September 2006 survey, which clocked in at 335 ms... more >>>