Subscribers to VoIP services increased by 83 per cent last year, new figures reveal.

Worldwide retail VoIP subscribers jumped from 10.3 million at the beginning of 2005 to over 18.7 million by the end of the year, according to broadband analyst Point Topic. 

The company also estimated that the number of people who paid for PC-to-phone calls during 2005 was over 4.7 million.

When combined with retail VoIP services, the overall number of paying VoIP subscribers adds up to just under 24 million, compared with 14.4 million the year before.

Japan, France and the US dominate the VoIP market in terms of subscriber numbers. However Germany, the Netherlands and Norway saw a significant number of VoIP subscribers by the end of 2005.

France is the biggest market in Europe, with over 2.8 million estimated paying VoIP subscribers, not including Skype users, mostly due to France's success with local loop unbundling and easy-to-use equipment.

In the UK, BT's VoIP offering had relatively few subscribers by the end of 2005, but was starting to see fast growth in the early part of 2006.

Asia Pacific saw the slowest rate of growth, mainly due to a slowdown in subscribers in Japan.

The retail VoIP market in China has yet to develop, although several operators are trialling services.

Government restrictions on VoIP mean that China remains in a trial phase, although some observers think that PC-to-PC and PC-to-phone calling has begun to dent Chinese fixed line revenues.

Retail VoIP numbers more than doubled in the US and Canada during 2005, with Vonage the biggest single operator.