Mocha use his nose and ring the windchime we hang next to the patio door. Vienna on the other hand usually jumps then runs to the patio door, if she doesn't see me behind her, she'll come back and jump up to get my attention.
My Charlie sits by the back door or very loudly paws at the door until we let him out. Sometimes he won't get off the back deck until I go with him. He needs me hold his paw while he goes potty. (what a baby! Boy does he have me trained!)
My corgi mix will come into the room you are, sit and stare at you and wag her tail. Duncan will stand and whine at you, and you have to pay attention to him. He's a whiner anyway (which drives me crazy!), so you have to be alert to his signals. Hence the piddle pad. Just in case I misread him, he goes to that, thank goodness.
I also have to go outside with Duncan while he goes potty. He won't go out by himself, and if you do get him to go, he sits right by the door and won't do his business. I contribute that to the fact the first 5 months we had him, we had to take him on a leash in the backyard due to not having a fenced in yard. Now that we have one, we still have to be there with him. Thank goodness the corgi mix, just runs out and does her business.
He does on occasion. Mostly when there are squirrels outside that he can see. Usually he doesn't ring unless he really needs to go out though. On the odd occasion that we suspect he's abusing the bell we leave him outside for a while. He doesn't like being out without his people so when he does come back in that's usually the end of it.