Quiz show junkies were once limited to shouting their answers at the television from the couch. Now, thanks to the advent of digital technology, wannabe contestants can play along with the TV, phoning in or texting their guesses for a chance to win as much as £30,000.

Just as punters enjoy the challenge and the cash, broadcasters are hungry for the extra revenue from interactive quiz shows. They are rushing to embrace call-TV formats, as they are known in the industry.

But ITV has taken the concept of interactive quizzes one step further, by yesterday announcing a two-year deal with emuse technologies, a Dublin-based developer of interactive TV applications, to produce synchronised interactive formats for cable, satellite and terrestrial TV.

In practice, this means that viewers sitting at home will be able to compete live with contestants in the studio in quiz competitions. They will log their answers via their digital set-top box - with ITV, emuse and the phone company sharing the dial-up revenue.

"It's the pinnacle of what you can do with interactivity," said the chief executive of emuse, Patrick Rainsford. "The compulsion for viewers is that spontaneous participation."

ITV's interactive controller, Jane Marshall, said the company wanted to expand its interactive applications beyond votes and competitions. "One thing we keep finding is viewers love games and quizzes. It's certainly going to be a very important revenue stream."

It has been suggested that ITV would launch a betting "multichannel" - that is, an interactive digital channel - but it is understood those plans have now been put on hold.

emuse and ITV - who have already worked together on programmes including I'm a Celebrity, Get Me Out of Here - have three interactive projects in the pipeline, which are likely to be shown in autumn. Although emuse will develop interactive applications for all ITV genres, the first shows will be quiz-based.

ITV has also been experimenting with the more basic call-TV format for quiz shows, where the presenter is alone in the studio and the only contestants are the viewers at home. Big Game TV was launched on the ITV3 multichannel earlier this month and will soon shift to ITV2.

BSkyB is running its own pilot of the format, called Sky Quiz Live, and Channel 4 is toying with developing a regular programme after a successful trial production late last year.

For the diehard quiz fan, there is an entire digital channel dedicated to interactive quizzes offering cash prizes. Owned by Optimistic Entertainment, Nation 217 has made winners out of 30,000 people and given away more than £1m since its launch 18 months ago.

"There is a long tradition of quiz content on TV," Optimistic chief executive David Brook said. "Rather than play vicariously, the technology now allows you to play direct."

Mr Brook estimates there are hundreds of thousands of people in the UK of all ages who participate in interactive quizzes - which is good news for broadcasters as they cast around for new sources of income besides advertising.

"In a world where advertising revenue is fairly static, there is an opportunity to grow secondary revenue by looking at the interaction between telephony and TV," Mr Brook said.

Broadcasters make money out of the call revenue generated when viewers phone in or text their answers to questions. Contestants are randomly selected to play, and the revenue from the call is split between the broadcaster and the phone company.

Industry revenue from call-TV formats has soared 35% in the past year, compared with 3% growth in advertising revenues, Mr Brook said.

Ms Marshall describes call-TV formats as "very fertile ground" for broadcasters. "It's a win-win. It's revenue-generating and it's something viewers find engaging," she said. Without any promotion, Big Game TV is attracting "quite impressive" audience numbers, she said.

The popularity of Channel Five's Brain Teaser programme, which entices at least a third of its audience to call in, is the talk of the industry. Five now runs extra questions in the advertising breaks of the following show to keep viewers
tuned in.

"There has been a fantastic response to the point where it's a significant revenue stream for us and [production partner] Endemol," Five's sales director Kelly Williams said.

Five has established a separate commercial development team to capitalise further on extra revenue opportunities such as call-TV.

At just 12 months old, the team is now bringing in more than £15m - 5% of Five's total annual turnover of £310m.

Optimistic's Mr Brook does not feel threatened by all the competition for the interactive quiz player. "They'll help grow the market for us by raising awareness of this type of entertainment," he said.

About emuse technologies
Dublin-based emuse technologies was founded in 1998 by serial entrepreneur Patrick Rainsford to develop a suite of enabling technologies to service the burgeoning global interactive television market. emuse has now succeeded in creating, developing and patenting those technologies and aligning with key players in the arena. The company now employs 70 people and has built a world-class team of software, media, mobile, content, business and technology experts with offices in Dublin, London, and Tokyo, and LA. Web: www.emusetechnologies.com