Things are progressing - at least my level of understanding. Rumaging through old treasures I did find an old wired phone that my mum used to have before she died. Taking the front plate off and plugging into the test socket I did the quiet line / ringback tests and I have to admit that the loudness of the buzz had disappeared, but there was still a much softer hum in the background. I can't say that there was no sound at all.
Secondly, I must mention that normally we have a splitter plugged in the phone socket. This carries the line to the phone base station, and also connects the Sky+ box to the phone line as per the Sky contract (for updates, monitoring etc..). I removed the splitter and tried just plugging firstly the old wired phone, then just the phone base station, the results were quite revealing. In each case the very loud buzz had greatly diminished, although the softer sound, referred to earlier was still there. I think that the splitter must be faulty, as when I replaced it and connected everything back up, back came the loud buzz when I did the tests.
To give you some further idea of our configuration, the 7800DXL Router/Modem is about 2ft from the phone case station, not much further from a surge protected power source (extension with eight sockets), and the TV which is about 3ft away (connected by an ethernet cable to the 7800DXL).
I am trying to think of a way to alter the configuration so that the 7800DXL is further away from all the jumble of wires and possible interference, but as you will understand one has to satisfy 'Senior Management', who will comment "you're not putting it there" - if you know what I mean
So I think I am a little clearer, but with work still to do. God willing I will go and get another splitter tomorrow, that will at least take care of that Issue I hope, then it is 'thinking cap time' to see if I can alter the configuration before I involve a line engineer from Beattie.
DSLstats is still showing a SNRM level of above 23 dB for the upstream, and around 3 dB for the downstream.
Many, many thanks for your help thus far - do you have any further thoughts?
Regards,
OldTimer