Ofcom has encouraged internet service providers (ISPs) to sign up to a voluntary code which would regulate how they advertise broadband speeds to customers.

The regulator said it was concerned that consumers may be misled when signing up to broadband packages which advertise speeds much higher than those received in practice.

Under the new code, broadband providers would be required to give an accurate estimate of the maximum speed a customer could expect over their connection, and give them the choice to shift to a lower package if the estimate was later found to be inaccurate.

Providers would also be required to make greater efforts to improve the speeds across their networks, and train staff so that they could better explain issues relating to broadband speeds to customers.

Ofcom noted in its report that consumer satisfaction with ISPs had fallen in the past year, and said that it would consider introducing more formal regulations if the voluntary code did not prove effective.

At present, most ISPs advertise speeds as being "up to" a certain number of megabits per second (Mbps), and explain in smaller print that the speed can vary depending on a range of factors, including congestion in the network and the distance of a home from its local exchange.

A Which? study in August last year concluded that the average speed achieved on an '"8 Mbps" broadband package was 2.7 Mbps, and that in some cases the actual speed was 0.9 Mbps.

So far 32 ISPs - which between them account for 90 per cent of the UK's broadband coverage - have signed up to Ofcom's code. Most of the major providers, including BT, Orange, and Tiscali, already offer line checks which allow a customer to gauge how fast the speed on the line is likely to be.

"We want to encourage real clarity for consumers about the actual broadband speeds they can receive and this voluntary code is a significant step in this direction," Ed Richard, Ofcom's chief executive, said.

A Which? spokeswoman said that the code was "a good first step", but added that it was "only voluntary", and that Ofcom would have to keep a "watchful eye" and consider regulation if ISPs signed up to the code and then did not abide by it.

"The new code won't improve speeds, but it will let customers make a more informed choice about their broadband package, and understand the issues that will affect speed, such as the time of day at which they use the internet," the spokeswoman said.

Broadband providers welcomed the code, saying it recognised that every individual's experience of broadband would be different and dependent on a range of factors, including the distance from the exchange.

The Internet Service Providers' Association (ISPA) said that while Ofcom's report focused on line checks, more emphasis needed to be placed on factors that were out of the ISP's control, such as the wiring within a customer's house, and which modem they used.

One ISP said that line checks, which are available on the internet, gave an estimated speed based on the distance of a home from the exchange, but the last 20m of a connection - from the box on the wall outside a house to the modem - was an unknown quantity.

"It's important not to confuse poor hardware performance with poor internet performance," the ISPA said.

Ofcom said it would also undertake the most comprehensive study yet of internet performance in the UK, and that it would aim to report back by the end of the year.

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