US Patent 9118819 Doorbell communication systems and methods

Doorbells can include a speaker and a visitor detection system having at least one of a button, a camera, and a motion detector. The speaker of the doorbell can be configurable to emit a first sound in response to the visitor detection system detecting a first indication of a visitor's presence. As well, the speaker of the doorbell can be configurable to emit a second sound in response to the visitor detection system detecting a second indication of the visitor's presence.