[trackbeo]

Suggestion: Name your carrier & location, and the CPE model number.  Thus someone knows if their experience might be helpful to you.

An experiment you could try is substituting an old bell ringer phone, or even a moderately-old AT&T slimline.  Does that work?  Then parallel it with your Beoline.  Does that work?  “Their end not mine drops the call” implies that something on your end is picking up and immediately hanging up, though it’s not clear where in the chain that something is.  A DSL filter added should both be unnecessary anymore, and should make no difference, which it doesn’t, so that’s good at least.