Thanks for your post. Sorry to hear that you have been having landline issues. How long has this been occurring? Do you have multiple phones and is it happening on all phones or if you have multiple sockets/phonejacks, are you able to try using those other phone jacks?
It's got progressively worse over a number of years but as we don't generally use it there's not been a problem. Only have one usable socket and have not tried another handset but I'm fairly sure it's a problem with the line.