The emergence of voice over IP (VoIP) technology has already had a significant impact on the traditional circuit-switched landline sector worldwide, but a new report from Analysys suggests that VoIP will have an even bigger impact on the mobile phone sector. The telecoms consultancy firm suggests that once 3G technologies are enhanced to allow for greater bandwidth transfer, there will be a compelling case for mobile operators to switch from circuit-switched voice to mass-market cellular VoIP.

Analysys estimates that by 2012, mobile VoIP revenues will total $18.6 billion in the US, a considerably larger sum than revenues generated from fixed VoIP services.

While mobile VoIP is just around the corner, fixed VoIP is growing steadily in the US, with a recent estimate from Telegeography pegging total US VoIP subscribers at 6.9 million in Q2 2006. Vonage reported 1.8 million subscribers as of the middle of 2006 with cable company Time Warner Cable following closely behind.

VoIP is a relatively recent phenomenon, so it is perhaps unsurprising to see subscriber forecasts differ significantly among research firms. According to comparative estimates presented below, there could be anywhere between 12 million and 44 million VoIP subscribers in the US by 2010. eMarketer estimates 32.6 million VoIP subscribers by 2010, up from 9.6 million at the end of 2006.