The body that regulates premium-rate telephone services has issued guidance telling users how to deal with porn diallers.

The leaflet from ICSTIS explains how to distinguish legitimate dialler services from those that reroute dial-up connections by tricking consumers. It also explains how to make a complaint if you think you have been duped into downloading a dialler.

You can download the leaflet in electronic format here.

Porn diallers reroute a dial-up internet connection away from your ISP's number and through a premium-rate telephone number, normally to a company based overseas.

Many consumers have found themselves facing bills of hundreds of pounds, with disputed bills for 2004 alone topping £2m.

ICSTIS has introduced a licensing scheme for companies that wish to operate such services, with strict rules about the kind and clarity of information that must be displayed on-screen before the internet call is rerouted.