Internet service providers (ISPs) are advertising unlimited broadband services which are anything but, according to uSwitch.

The price comparison site said many of these so-called unlimited services come with what is called a fair use policy (FUP). Because these FUPs effectively place a limit on how much consumers can download, ISPs should therefore be banned from advertising these services as 'unlimited'.

The call comes after a study of nine major ISPs carried out by uSwitch showed that restrictions that an ISP could impose on its customers under one of these policies comes as total surprise to most consumers.

Telecoms regulator Ofcom found that seven in 10 people believe they have no download limits.

Because they are unaware of these restrictions, consumers are happily consuming bandwidth by using new internet services such as movie downloads and broadband TV; the result is people are being disconnected or having their service severely restricted because they are unaware they have 'overstepped the mark'.

uSwitch said one problem with these FUP is that apart from being misleading, ISPs do not quantify what they consider excessive usage or specify the limit that would lead to disconnection or restriction of a service.

The website said it was an industry-wide problem and it had found each of the nine major ISPs it surveyed would be prepared to do this to customers who used their service ‘to excess’ worryingly often and without warning.

“If these policies are to be classed as 'fair', broadband companies need to clearly define these limits and explain to customers what will happen when they are exceeded," said Steve Weller, head of communication services at uSwitch.

He warned that the situation for consumers will only get worse as services such as broadband TV, video, TV programme downloads and other new services come online. For example a 45 minute TV programme such as Lost, would use up around 350Mb while a two-hour movie would use up to 900Mb.

It could mean as many as nine million broadband users could fall foul of FUPs.

AOL, identified in the study along with Be, Orange, Pipex, Sky and Virgin Media as ISPs offering an unlimited service, with a FUP that could see an excessive user kicked off these services, said the "vast majority of broadband users are unaffected by FUPs". It also said it took action against excessive users to safeguard the service for less heavy users.

Tiscali, which along with BT and Toucan also said FUPs were the fairest way for most consumers. But it pointed out it would manage excessive use at peak times rather than disconnect people and its FUP was "becoming industry standard across all of the major ISPs."

But uSwitch does not agree. It has therefore asked both the Advertising Standards Authority and Ofcom to consider banning ISPs from advertising unlimited broadband if a FUP is also in place. It has also called for standardisation of FUPs across the industry and for compulsory alerts to be given to consumers before an ISP considers disconnection.

Because of the number of different broadband deals available, the price comparison site has also launched a ‘Usage Barometer’ on its website. The aim is to help broadband users understand the level of download limit or ‘cap’ that they require.

They can identify how they spend their time online via a series of sliding bars. They will then be told whether they are a ‘light’, ‘mid’ or ‘heavy’ user and will be advised of the download level they will require for their broadband service.