New rules are to force TV quizzes to inform viewers of their chances of getting on air and give more information on the cost of taking part.
MPs have called for greater regulation of TV quiz shows
Premium-rate services regulator Icstis said its new rules would "go a long way to restoring trust" in TV quizzes.
The measures will come into force in four weeks' time.
Media regulator Ofcom is conducting an inquiry into premium-rate phone lines on TV programmes following allegations that some shows have misled callers.
Icstis said it had worked closely with Ofcom, broadcasters, producers and telephone companies, "who have all been supportive in making sure that the changes could be introduced as soon as possible".
"We believe these new measures, which are designed to address the concerns that have been raised recently, will go a long way to restoring consumer trust in this form of TV quiz," said Icstis chief executive George Kidd.
The rules being added to existing safeguards are:
- A viewer's "chances of acceptance or rejection" must be permanently shown and updated at no more than 10-minute intervals.
- A presenter or voice-over must explain pricing information at least every 10 minutes.
- Participants must receive warnings about costs for every £10 spent in a day.
Last month, Ofcom warned broadcasters about a "growing trend in complaints" about phone-in quizzes.
It called for "rigorous" procedures to prevent the broadcast of "challenges that are almost impossible" and "inaccurate and/or misleading clues".
Trust could be lost between the broadcaster and audience, it warned.
It currently has over 20 investigations under way into TV phone-ins but some of those relate to the same show.
Icstis is investigating how phone lines were operated on 15 separate shows, including Channel 4's Richard and Judy and BBC One's Saturday Kitchen.