VoIP providers are still far too unreliable in comparison to their fixed-line brothers, a study has found.
A report from Web performance analysis firm Keynote Systems found Internet telephony isn't up to the same standards as traditional landline telephone networks and that a lack of clarity and audio delays will inhibit take-up among consumers.
The study looked into the performance of a number of VoIP providers, including Skype and Vonage, over a five week period.
Vonage came out tops as the most reliable provider but could still improve on its dropped calls ratio, according to the study, while AT&T's CallVantage picked up the gong for best audio quality but suffered from geographical differences in audio delay.
However, the report acknowledged that not all of VoIP's faults could be laid at the feet of the service providers; the underlying networks also play a part in reliability and clarity.
According to separate research from analyst house Infonetics, service providers will nevertheless be investing heavily in the world of VoIP. They spent as much as $1.7bn ($960m) on the technology last year — and that figure is expected to grow to $5.8bn by 2008.