Sometimes all companies need to start sending people expensive texts is a phone number on a website.
Often consumers are tricked after falling victim to so called typo-squatting.
PhonepayPlus says that's when people mistype common web addresses by as little as one letter.
They can then be directed to look-a-like sites that promise cash or expensive gifts where all people have to do to claim is enter their mobile number.
PhonepayPlus says it's only had 38 formal complaints about this type of scam but is worried the problem could be much more widespread.
Shirley Dent is the watchdog's director of communications: "We're not talking about the vast majority of good [premium rate service] providers.
"We're talking about the few problem providers who cause problems for consumers, problems for the industry and problems for us as the regulator."
In February, PhonepayPlus fined two companies £100,000 each for breaking its code of practice after it typo-squatted several sites.