I installed multiple Hikvision DS-2CD2132F-I-2.8MM cameras along with an Hikvision NVR at my home about a year ago now. None of these cameras have a microphone but (coming off the camera) I do remember having an additional plug next the to the Ethernet port. Is this extra plug for adding a microphone? I’m thinking about adding a microphone to one of the cameras but I don’t know how to go about it? Can anyone shed some light on how I would do this? Thanks.