I don't think it would be impossible. It is a filtered faceplate. A filter filters things, but doesn't necessarily completely block them.
Is it a cordless phone or a corded one? I can imagine some small 'crackle' noise getting through from a corded one, and maybe quite a bit of low RF noise from a cordelss.
Moved (with trepidation turned relief) to BT Infinity 2 for upload speed. Happy BE user for several years.