Short version - with an NTE5c and a mk4 faceplate, you have the option of wiring a phone-only extension from the 2/3/5 points behind the removable faceplate. If you only wire 2 and 5, are the phone-only extensions still filtered properly, without the need for separate micro filters?
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Modern wisdom suggests 3 (the bell wire) isn't required and can induce noise on the line. However, a friend's connection, which I helped rewire, was struggling for speed after moving to BT Infinity fibre. He's put up with it for 18 months, was on the cusp of ringing BT, before I suggested he tried the test socket. Low and behold, it's gone from 27mbps to 45mbps.
I then suggested plugging the telephone (the only device plugged into the system, other than the BT Hub) back into it's extension via a microfilter. The speed boost seems to have stayed there.
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So I'm left wondering if me not wiring from 3 on the NTE5c to the extension socket, has caused this issue/means it's not being fully filtered? I watched an informative YouTube teardown video of an NTE5c that explains how the extension wiring is isolated/activated by the faceplate. I know that by using 2 and 5, there will be no VDSL signal present at the extension, but is all other necessary filtering still performed without 3 being connected?
On an NTE5a, I know the extensions were taken from the back of the faceplate itself, which presumably makes a difference to how the filtering would/wouldn't work. Most of the posts I can find online relate to this earlier setup and not the NTE5c/mk4 faceplate.
Thank you for any help/reassurance in advance.
