first of all it'd be a dedicated emergency line, like 911 to Operations center direct.
Second of all, if that is not fast enough, then humans are insufficient too. You cant just magically get people to act (a lot of the time they'll do the wrong thing and fail to even recognize what situation they're in at the moment) Notice how bumper to bumper traffic is pretty bad for EMS, people do not know how to react.
Honking your horn and getting the person to pull away is pretty fast. By comparison it takes several minutes to get through to 911 where I live. Not to mention most humans would know better than to park in front of a fire department driveway or drive through caution tape.
Second of all, if that is not fast enough, then humans are insufficient too. You cant just magically get people to act (a lot of the time they'll do the wrong thing and fail to even recognize what situation they're in at the moment) Notice how bumper to bumper traffic is pretty bad for EMS, people do not know how to react.