Try removing the door and see if the ringing stops.

I removed some ear wax and the ringing stopped for a while.  

Starise ...
because if a person comes to the door and knocks we don't always hear it.
...
Of course if the person is invisible it won't help much.

Of course you don't! NEITHER DO WE!
 
We got our headsets on, and listening to music!
 
We need to re-invent the doorbell for musicians ... a nice electronic and colored cowbell that shines on the corner of your screen, or on the wall somewhere, when it rings! This way we don't have to have an excuse to ignore the doorbell!
 
If only the wives could get that smart, we would be in trouble, you know?

Hmm..let's see remove the door. Check. Put a cover over the bell. Check.
 
Seriously I haven't done any of that yet. If it keeps up though I'll need to resort to more drastic measures.  It hasn't happened now for at least a week. Maybe I'm in the clear.
 
If this is a ghost bully, then I'm hoping that it went to the house next door. I think it liked my doorbell because it played different tunes. When I set it for random tunes it was like a free juke box. What ghost wouldn't like that? Or maybe a mouse fell for the reward system. I bite wire, and I get free music.

I'd like to buy that door bell because every time mine rings, there's someone there.  Mormons, Jehovah Witnesses, cable TV salesmen, pathetic looking looking kids with sad eyes selling candy for some youth organization, you name it.

Mod Bod
I'd like to buy that door bell because every time mine rings, there's someone there.  Mormons, Jehovah Witnesses, cable TV salesmen, pathetic looking looking kids with sad eyes selling candy for some youth organization, you name it.

scouts?

Landshark?

If you were pathetic looking you would have sad eyes too...
 

Craig I haven't ruled out landsharks.
 
Mod Bod, Luckily I don't get a lot of visitors. Even on Halloween we might get two trick or treaters at the most...and that could have been the same kid dressing up twice.
 
Two nights ago we got a ring from the amish next door who needed an email address because the son is going to the grand canyon on a hike. In 12 years we had one Jehovahs Witness come by, but I was out back and they dropped off some kindling for my fires. We have had neighbor kids come by selling subs. I usually buy a few of those because they're local neighbors and I help their ball teams out. That was months ago. A Mennonite guy and his family stopped by two months ago and said they were raising money to go to the creation museum. They were selling chicken pot pies. I don't personally believe that the earth is only 6000 years old but I gave em' a 20 and said keep the pies. I have no idea if they were legit or not.....I don't get bugged much that way though....my telephone is the thing that drives me crazy....well aside from the invisible person who rings my bell.

Plumber.
Candygram.