When checking my Grand-Daughter's SKY-provided system I was appalled to find that the Download Speed was below the 3 Mbps level, although apart from normal line-routeing distances, she is decidedly nearer the same Exchange that I typically get 14 Mbps from, on EE/Orange.
I carried out the SKY QLT at the NTE with an old corded phone, getting the response-
"Quiet; but there is an ECHO on the Line"
There were no obvious noises apart from a very quiet hum, which also occurs on my own Land Line.
I did NOT HEAR any obvious ECHOES or echoing.
From my working background, I appreciate that echoes, standing waves etc are likely to have a bad effect; BUT in trying to get a better idea of the specific cause in this instance, I have not yet found any information.
Have any of you direct experience and knowledge of this INAUDIBLE ECHO situation?