@el355,
I sympathize, and don't have answers.
When I first moved to this new place, I got a lot of fax machine calls - annoying, but they gradually stopped.
Next came one ring calls around 5:30 or 6 am, once in a while earlier, even way earlier. Usually I figured it was someone who was going to pick someone else up to go to work, calling that person with one ring to wake (him) up. Eventually that stopped. I can just picture the arguments - I called you, no you didn't, yes I did, no you didn't. I didn't have caller id back then, and couldn't get to the phone in time in the first place even if I did.
I have also woken to ring like sounds that I've since identified as my refrigerator - not the doorbell or phone.
In my case, I thought it was just dismal stuff and not harassment.
I guess that if I were you, I'd write or inquire to your phone company for advice.