a dull hum is normal on cordless phone anything else can be a problem see if stays stable now faceplate clipped securely back in place but if not may need phone engineer for line hiss
well I’d have no landline to take calls if I tried that over 24hrs, only broadband, but if it persists I’ll try it .
it’s dropping about once a day at the moment.
So the filter is in the faceplate?
or are there 2 sockets underneath, mine only has the test socket?
The face place has 2 outlets - dsl and phone- and is filtered
the test socket is not filtered so you need to use a filter and then you can connect both hub and phone then leave and see if that helps stability