I tried a quiet line test and their is a low level hum on the line.
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of course BT say their is "no Problem"
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Try the quiet line test from the test socket, if there is still a hum on the line report it as a voice fault, NOT a broadband fault. This sounds like an unbalanced line fault, a broadband test will not necessarily show a fault under these conditions. Get the voice side fixed first.l
This is what I had December 2015 (
noise on line) if you jump to 1 mins you can even hear our HH4 re-syncing up and this also happened while talking to BT when I tried to report it as a voice fault, BT did some tests and said there was no fault detected, even though they could also hear the noise.
And before you ask, no it wasn't an internal fault, all was plugged into the test socket.
It just shows you have rubbish the BT overseas call centres really are.
We just put up with it until our FTTP was installed.
Paul
BTBroadband - Infinity 4 - 310Mbps (down), 31Mbps (up)
TBB Speedtest