BT Wholesale has said it will be offering its ISP customers a hardware filter that improves customers’ broadband by filtering out electrical interference in the home caused by TV’s, fluorescent lighting and home wiring.

The I-Plate (patent pending) screws into a phone socket in the home, and BT claims that trials of the technology showed filtered lines enjoy faster speeds and a more stable connection.

After a survey of 36,000 lines, BT said filtered lines typically showed a speed hike of up to 1.5Mbps, with some lines showing an improvement of as much as 4Mbps, although BT has warned higher speeds may be unattainable.

BT say the filter extends the geographical reach of a broadband service by around 10dB, and claim that households that are further away from an exchange could see an improved service, which other previously out of reach from the service may now be able to get it.

Ian Fogg, research director at JupiterResearch, told silicon.com that the move is “a tactical measure” by BT “to make the best of current broadband technology”.

He said: “It should give some small improvements, but it’s very much BT trying to prolong the life of putting broadband over telephone lines. If BT was being more aggressive with rolling out optical fibre, which gives a big step change in broadband speeds, this announcement would be much less significant.”

He added that some ISPs already offer ways for customers to maximise broadband speeds, such as encouraging customers to plug their broadband modem into the master socket rather than over an extension line, and providing a broadband router with the same chipset as the customer’s local exchange.

People who want to use the I-Plate will have to have a BT NTE5 master socket and extension wiring in their home. It’s estimated that seven out of 10 UK homes have the affected master socket and home wiring — some nine million households.

BT said the reason for broadband interference is an antenna effect produced by the “bell wire”, which is a third wire that runs alongside the pair of wires carrying the telephone and fat pipe signals, which forms part of the extension telephone wiring that runs around most homes.

The I-Plate works by isolating the bell wire and filtering out interference. The device can easily be installed BT customers and it just fits behind the front and back plate of the master telephone socket.

BT Wholesale will offer the I-Plate to its ISP customers may or may not choose to pass on the cost of buying the hardware to customers, according to a BT spokeswoman.