A colleague at work recommended this to me. It sounded a combination of unlikely and plausible so I thought what the hell. After BT making it very difficult to order with a credit card, I ended up using Paypal. If you’re with BT for broadband, they send them to you for free, just for asking. For the rest of us, its £7.99
The idea is that the original design of the BT socket provides a small current as a ‘bell ringer’ for the days when the bell in the phone was powered by the phone line. With extensions, particularly, ADSL connections can pickup additional noise from this, and the iplate is an extra filter to fit to the main socket of the connection.
So, does it work?
Of course, these measurements were not taken immediately, and there are a number of things that could interfere with this, but even so, its pretty impressive!