British Telecom is currently the best performing ADSL UK internet service provider (ISPs), says a net survey.
The type of cable coming into a house can affect connection speeds
Data on all of the leading consumer ISPs in the UK were collected by internet testing firm Epitiro.
The firm used software that connected to services every 15 minutes to test various features including download times and connection failures.
Results from 10 locations around the UK identified BT as top followed by Virgin, Demon, AOL and then Orange.
The survey did not take into account broadband provided by cable companies such as NTL Telewest.
Epitiro has been conducting tests of broadband services for the last three years. The information that it collects is normally sold back to telecoms providers and ISPs.
The report is the first time that results have been released to the public.
In terms of internet performance, BT Yahoo topped the overall rankings for the period April to June 2006," said Gavin Johns, managing director of Epitiro. "BT was also found to provide the fastest service as a percentage of its theoretical maximum."
Even though ISPs may offer 2Mbps or 4Mbps services, consumers will never receive a service that reaches these theoretical speeds. Factors such as the amount of people using the web or the age of cables connecting a house to the network slow down the connection.
Epitiro use more than 250 "monitoring agents" installed in 10 locations around the country to conduct their tests.
Multiple ISPs are compared at each location to make sure that factors such as distance from telephone exchanges do not influence the results.
The same speed services from different ISPs are compared together.
Each agent tests 10 different aspects of a service every 15 minutes. These include the time it takes to connect to a service provider, how long it takes to download a website or how long it takes to upload content to the web.
The company collects real time data and collates the results every three months.
As well as indicating which services are performing the best overall, the data can also highlight which services perform best in different areas.
"Virgin, BT and AOL were the fastest services to actually connect to the internet, while Pipex, Orange and BT were up to four times faster than the industry average at delivering e-mail," said Mr Johns.
The results of the tests do not indicate which ISP is best to use or represents best value for money, said Mr Johns. Other factors such as the price of a service or the level of customer support are not taken into account.
"It's hard performance data and nothing else," said Mr Johns. "That's how we measure them and that's how we rank them."