The number of US consumers turning to IP telephony solutions has soared from 6.5 million in mid-2006 to 11.8 million by the second quarter of this year, industry analyst TeleGeography has revealed.

Based on current trends, the research group estimates that by 2011 some 23.3 million people will be wired into VoIP phones.

However, despite the success of American cable providers in spurring on the IP telephony revolution the US market is still lagging behind its European counterpart.

In Europe uptake of VoIP solutions has accelerated rapidly since last year, due in large part to the liberalising of access to local copper loops managed by incumbent telecoms providers such as Deutsche Telekom and BT.

Aggressive competition and pricing and active participation by incumbent operators in the VoIP market have also yielded positive results, with TeleGeography projecting that by 2011 VoIP penetration in Europe will be twice as great as in the US.

"VoIP service in the US has emerged as a mainstream service that is causing traditional service providers some headaches," commented TeleGeography analyst Stephan Beckert. "However, in Europe VoIP could fundamentally change the structure of the fixed-line market."