I used to live in an apartment complex that had an electronically controlled front door to the building, coupled with a very annoying call box.
The called party just has to press 9 on their end, front door unlocks.
This method is meant to selectively admit guests to the building.
What happens if you forgot your card key? You’d have to choose your roommate’s name in the list, or hope some stranger would let you in.
What if a robot answered and would let you in, provided the right PIN was entered? Easily done…