Classical Chinese Homes: Door Bell, Door Knocker, or Something Else?

[chomiji]

I'm having no luck with Google searches on this (my Google technique is usual pretty good), and though I have found some decent diagrams of traditional Chinese homes, they don't go into this level of detail.

When a visitor arrived at a non-lordly Chinese home (say, a lesser merchant's home) in the "classic" Imperial period that is popular for costume dramas, how would he announce his presence? Would he ring a bell, knock on the door, or what?

I'm guessing that a well-off home would have a doorman of some sort, who would announce a guest, but what about a house that had no servants, or only a scullery maid or something?

Thanks in advance for any input you might have.