Internet service providers are still dramatically exaggerating the broadband speeds they actually deliver, according to the latest research from Ofcom.
The watchdog found that the average promised speed has risen from 13.8Mbit/s to 15Mbit/s since December 2010, while actual speeds have risen from 6.2Mbit/s to 6.8Mbit/s.
BT was one of the worst offenders. The firm's 'up to' 8Mbit/s service delivered a maximum of 4.3Mbit/s over a 24-hour period, while its 'up to' 20Mbit/s fared even worse, peaking at 8.9Mbit/s during testing.
There was some good news for BT, however, as the research found that its Infinity service had the highest upload speed of almost 9Mbit/s, twice as fast as any other provider.
Plusnet, Orange and O2 also failed to deliver on promises of up to 20Mbit/s broadband. Only O2 managed to creep into double digits at a peak of 11.7Mbit/s, while Sky fared worst, hitting just 8Mbit/s at its peak connection speed.
Virgin Media performed far better than the rest, its 10Mbit/s service offering between 9.3Mbit/s and 9.6Mbit/s and its 20Mbit/s service ranging from 17.6Mbit/s to 18.7Mbit/s over a 24-hour period.
Virgin's 'up to' 30Mbit/s service actually returned results above this speed, hitting between 30.7Mbit/s and 31.3Mbit/s over a 24-hour period.
Jon James, executive director of broadband at Virgin Media, used the results to bash the firm's competitors, and called on the Advertising Standards Authority (ASA) to resolve the discrepancy between promised and received speeds.
"We remain concerned that people paying for fast broadband are being misled, and it is absolutely essential that consumers have all the information they need to make an informed choice," he said.
"We once again urge the ASA to bring about a rapid change in the way broadband services are being advertised."
Ernest Doku, technology expert at uSwitch.com, said the results should encourage customers to make sure they know what speeds they actually receive.
"We support Ofcom's recommendation that adverts should show the range of speeds delivered to at least half of customers, and hope that this will be finally approved by the ASA in the autumn. This issue has been going on for too long," he said.
"In the meantime, the actual speed customers experience depends on factors such as the quality of their line, and the distance from the exchange. We advise any customers who are concerned to run a speed test and discuss the results with their provider."
Simon Harper, director at ISP Eclipse Internet, said that it is imperative for service providers to be honest with their customers.
"When looking to purchase broadband, businesses and consumers should also look at the average speed their potential ISP is attaining and whether they have any service level agreements in place," he added.
"Only then will they be able to guarantee a minimum level of service or response time to network issues. Having consistent speeds are vital for businesses as more enterprise applications move from the desktop to the web."
The figures come after it was revealed that the UK had failed to place a single city in the global top 100 for broadband connection speeds based on data from web content firm Akamai.
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