The measures have been introduced following a series of scandals involving phone-in voting and phone-in competitions in 2007. Ofcom has levied heavy fines recently against many broadcasters and radio companies after concluding investigations.
Ofcom first proposed tightening the rules governing these channels in April 2008.
The changes come into effect early next year and mean that PRS may only be included in TV and radio programmes, such as phone-in competitions and votes, when they are related to the main editorial purpose of the show.
Ofcom emphasises that this move will not affect programmes such as Who Wants To Be A Millionaire? and Big Brother where phone-ins are integral to the structure of the show.
If broadcasters wish to promote PRS services more extensively than permitted under the new rules, then these services will fall under the strictures governing advertising and be regulated under the Advertising Code.
Channels that could be affected by this are the Participation TV (PTV) channels that are based on promotion of PRS. These include specialist quiz, adult chat and psychic channels.
The Code currently limits advertising of PRS of a sexual nature to encrypted channels and also restricts the promotion of PRS featuring live personal psychic services.