In reply to a post by astoria555:

I think the target SNR margin has probably been increased, most likely due to previous bad line quality and disconnections.

This will almost certainly be true.

... and we also have a burglar alarm that somehow connects to the alarm though I'm not sure how.

Bingo! I assume you mean "manages to connect to the phone"?

That needs a filter fitted at the control box end, and I will lay odds it doesn't have one. Was it installed before or after you got broadband?

Another thought - do you have a Sky box?

It looks like you have a split pair on the master socket, can't tell which cable it goes to but the pairs are orange / blue and green / brown, where you appear to have 2 blues in one terminal and an orange and green.

Someone actually came round to the house to fit a filter to the alarm before we got broadband. I do have a Sky box but no longer leave it plugged in as out of contract, it used to have an extension cable that plugged into one of the sockets.

I guess I have star wiring as everything is so old so looks like the best thing I could do is have a new NTE5 plate fitted so that I can just run the broadband straight from that.

What is a split pair, is that likely to be causing interference?

Edited by deleted (Thu 06-Jan-11 19:55:03)

Telephone wiring works using pairs of wires twisted together throughout the cable length, these twists help cancel out interference picked up by the wires, a split pair means that the two wires are not twisted and so act independently and can actually cause more problems.