New rules to protect TV viewers who take part in phone votes and competitions are to be introduced after a string of scandals last year.
Ofcom hopes the changes will restore faith in TV competitions
Broadcasters must get permission from premium rate regulator PhonepayPlus before setting up any phone-ins.
And all premium rate set-ups must be independently verified, with media regulator Ofcom due to carry out unannounced spot checks.
Richard and Judy and GMTV were among the shows hit by competition problems.
Channel Five's Brainteaser and the BBC's Blue Peter were among the other programmes with irregularities.
Ofcom has fined broadcasters more than £3.5m in total after some entrants had no chance of winning, while winners were faked in other competitions.
Under the new Ofcom rules, broadcasters will also be directly responsible for handling all phone calls, e-mails and letters from viewers.
Ofcom chief executive Ed Richards said: "These measures will ensure that broadcasters are directly accountable and give greater protection for all viewers.
"Ofcom will not hesitate to take firm action with broadcasters who step out of line and mislead people."
Ofcom wants the third party verification to be in place by the end of June.
Meanwhile, PhonepayPlus which carries out premium rate regulation on Ofcom's behalf, has set a number of conditions broadcasters must meet before they can run such phone-ins.
They include ensuring all correct entries are considered and closing lines promptly when an announcement is made to that effect.