I have BT broadband on a long,long extension with relevant filters so I can use the phone as normal while on the internet with the computer. No probs with speed, tested without filters and connection was same at times crap but mostly ok.
Most if not all internet connection contracts are alleged to state before the speed figure those two most common magic words of advertising, they are 'UP' and 'TO'
In short they can't guarantee the speed. I've read of many complaints about this.
Nobby
February 2009