At present the industry is regulated by the Independent Commission of the Supervision of Telephone Information Services (ICSTIS) which has the power to fine offending companies. "Ringtone services is a youth market, often involving children, and we are concerned that there are problems associated with this," an ICSTIC spokesperson said. "But there are thousands of operators, the majority operating within our code of practice."

One of the most complained-about companies is Jamster which offers the Crazy Frog and Sweetie The Chick products. Children who sign up for one ringtone don"t understand that they are buying one ringtone but also signing up for a high- rate subscription service.

mBlox, which provides the premium-rate numbers to Jamster - is being investigated by ICSTIS. The inquiry centres on the alleged failure of the company to make it clear that by signing up to the service, customers were agreeing to pay for a regular service, rather than a one-off ringtone.

The first thing to do if you getting unwelcome texts from a premium- rate number is to reply to the text message with the word "STOP" in capital letters, without the quotes, which is the industry standard way of unsubscribing.

Useful Links & Numbers:

ICSTIS: 0800 500212
http://www.icstis.org.uk/