Worldwide subscriptions to Internet-based television platforms are on track to reach 19.6 million subscribers in 2008, a 64 percent increase, according to analysts at Gartner.

Revenue from worldwide Internet protocol television is forecast to reach $4.5 billion, up 93.5 percent from a year earlier, with Western Europe boasting the largest number of IPTV subscribers and North America the largest market for IPTV revenue.

It forecast that 1.1 percent of households worldwide would be using IPTV in 2008, and expects that to rise to 2.8 percent by 2012.

"Before 2008, the IPTV operators' emphasis had been to spread their footprint and effectively provide a 'me too' solution to cable and satellite, said Jopling. "In the future, especially in the developed markets, we will see an emphasis on innovation and differentiated pay-TV services."

Gartner defines IPTV as a managed broadband network which delivers high picture-quality television and video content to a user's TV set via a set-top box. Content delivered over the Internet or only to a computer is not included.