What lock system do you recommend for main entrance of a Duplex

[Matt N.]

I have a rental two unit building which has a main entrance door that tenants tend NOT to shut because the door opens either by key or someone physically opening it from inside which is a hassle for the the upstairs tenant. I want to fix this and increase security. I want to have a doorbell that any apartment's code (3) is entered it rings that persons phone (3-5) and the recipient of the call can open the door using his/her phone. Video would be a plus. I also want to add a camera on the side of my property to record trespassers.

I'm looking at Ring doorbell now. But I don't know if Ring can be used to open door for 3-5 different people (phone numbers). Does anyone know?

What are you investors or property managers using that is working for you?