I've called the emergency number for police three times, when my girlfriend and I lived in a less than reputable area.
Once, when I was home alone, and a drunk/high guy showed up at the end of the hall and kept arguing, at a fairly reasonable volume, with what I think was his ex girlfriend through the door at about eleven o clock at night. This went on for a good hour, and I kept myself sort of "alert" to it, because the dude's voice carried, and he was just down the hall. He got more and more paranoid, eventually started pleading to be let in, and then almost instantly got violent, and started hammering on the door. Called the police right away, was on the phone with the dispatcher giving her a play by play and directions, put my shoes on and was psyching myself up to go down there and see...hell, I don't know what I was going to do, when I heard this guy break the door down. I kid you not, about ten seconds later, and 30 minutes after the call, I'm heading out into the hall to see if he's in the apartment yet so I can update the dispatcher, giving the play by play, wondering if I should go down there. I hear squealing tires. Maybe 15-20 seconds later two cops are up the stairs and rushing into the apartment, screaming at him to get on the floor, etc, and there's a woman inside screaming bloody murder. Cops subdued him, arrested him, and came down to take my statement. I guess he'd lived with his ex girlfriend and her boyfriend, and was a lazy, drunken *******, so they kicked him out.
Then, about six months later, I heard a few gunshots across the parking lot, sounded like they were coming from inside the apartment complex. Called the cops and they brought three squad cars and a chopper within minutes, swept the area, etc. They didn't find anything, so they left. Couple hours later, more gunfire. Called the cops again, same deal. Same result. Couple hours later I saw some little kids playing with fireworks. I felt like a dumbass.