When a person picks up the phone to call 9-1-1 during an emergency, the expectation is that a dispatcher will pick up immediately, quickly determine the nature of the problem and then send help in the form of first responders. 

In many cases the dispatchers have to work off of incomplete information, from a person who is in crisis or is making the call during a chaotic scene. There might be an answer from a coherent person speaking clearly to describe what’s happening, but sometimes all the dispatcher can hear is screaming in the background or sounds of gunfire and has to send help over with scanty details about what to expect.