Since it seems many building managers are reluctant to upgrade to the more modern intercom systems, I found a way to make my buzzer (just for my unit) smart.
It your buzzer system dials a phone number and then you need to press a digit (like 6 or 9) to unlock the door when someone buzzes, then it will work for you too.
Tested it using different intercom brands and also got approval from my HOA to do it.
The secret is to swap out the phone number you use with a virtual phone number (costs a few $ per month) that allows you to automatically answer the buzzer calls based on the rules/ schedules you set.