yes! We trained Shaye to do this, because we could not see when she was standing at one of our doors. We hung two bells on lengths of ribbon and put one around the door handle of the back door, and one around the handle of the sliding door. Each time Shaye indicated she wanted to go out, or when we decided she should go out, we took her paw and hit the bell with it. When she ran to the door to go out, we'd ignore it once or twice and then go with her and help her ring the bell - in less than a week she had caught on and began ringing the bell herself so we'd know she was at the door. If your dog keeps ringing the bell only when it really needs to go, it's a wonderful assist, especially if you can't see all the doors, like we can't.
HOWEVER, one word of caution: After a while, Shaye began ringing the bell all the time so she would be taken out, whether she needed to go or not, just to run around. We fell for it at first, then realized she was playing us, and now both girls go out on a regular schedule; we have figured out how long they will hold, and what they need to do when. So, no more bells.
I laughed so hard when I read about Shaye and the bell. This is exactly what happened to me also. Literally we would come in from outside and my boy would go straight back to the bell. It became his "I want attention/play/outside/walk/food" bell. I keep the bell there mostly so if someone else is watching him they know he needs something, since he is a relatively silent dog. I have to take the bell down and hide it every once in a while to get some peace.
I wanted to try this, but now I am considering not trying it. For one, I can see Kipawa gnawing at whatever the bell is hanging from. Secondly, he is clever and would definitely figure out he gets our attention whenever he rings a bell. So, we will stick with the routine we are using - upon waking up, after eating, after playing and after sleeping. So far it is working quite well, and only screws up when we forget. Humans are part of the training too! :)
Would it make sense to put the bell somewhere other than the door so that it won't be associated with just going out? Maybe somewhere close to the door but not necessarily on the doorknob.
The breeder that I got Malu from told me to make sure that the dog goes to the bathroom every time you take them out when you start bell training. That way the dog associates it with going to the bathroom, not going outside. I would also expect it would be best to bring the dog back in immediately after the business is done.
My Gossy has this habit of running around the perimeter of the room when she needs to go potty. Even in the midst of playing, she'll stop and do this perimeter run. It's a sure sign (too bad it's a self taught thing). Works better than the bell because whatever room I'm in, she'll come in and do it. Out we go.