Isn't this called dial tone?
I was assuming the buzzing noise is over the top of the dial tone, maybe the OP can clarify.
As soon as i press the first number to dial all the buzzing goes away, never had loud buzzing before dialling in the past, never.
Just checked the router stats and being on a long line 56db atten we have been connected at 3.7mbps down and 620 up.
Now connected at 4.4mbps down and 1066 up, sky have something which checks the line dont they? and resets it.
Any chance the buzzing is caused by setting the BB to high and interfering with the line,but is perfectly ok to leave as it is?
If you go out to play keep away from that "MAINE ROAD".