ADSL broadband Issue

My ADSL broadband with Virgin has suddenly become very unstable, I have had BT check my phone line and no issue reported - I can only get stable broadband when I connect my landline as though I am making a call - I now turn phone on and then leave it far away such that I do not hear the howler tone - anyone got any clues as to why I need to have phone on to get stable broadband ? I have tried different modems & ADSL filters - but same result - is this likely to be an issue with master phone socket ?

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Is your phone wireless this could be interferring with your wireless network. Any other wireless devices may not give off stronger signals when your phone is stable too.

It all depends on your home and its devices in it, and how things are laid out.