The BBC should reduce the amount of money it spends on its red button service, a BBC Trust review has said.
The report found while it was the UK's most used interactive TV service with 12.7m users per week, its cost - £39.3m last year - needs to be reduced.
The Trust recommended a less varied service between digital TV platforms to lower distribution costs.
It also suggested it focuses on its digital text and live events content instead of covering various genres.
The review looked at Red Button's performance, including usage, quality and value for money.
It noted the most popular aspects of the service was its news, weather and sports pages, as well as its live coverage of Glastonbury, Formula 1 and the Olympics.
It recommended other "more experimental content" should only be commissioned when there would be little cost in producing it or where "clear benefits can be identified".
But more than £20m of the Red Button's running cost is spent on delivering the service to Freeview, cable and satellite viewers - who each receive a different level of service depending on which platform it is viewed due to its technical capabilities.
"Red Button reaches a large audience and is effective in helping the BBC promote some of its public purposes," said BBC Trustee Diane Coyle, who led the review.
"It is not as popular as the BBC's other interactive services such as the iPlayer, however, and its overall costs - particularly for distribution - are substantial.
"The Trust will therefore look to the BBC Executive to reduce costs when and where possible by focussing on the aspects of the service that are most successful to date," she added.
The review began in September 2009 and included a 12-week consultation with more than 5,600 licence fee payers.