He did not call 911. He called the non-emergency number. This is the number you call to report suspicious activity. The military has the same set up and I have used it last year. Some clown was taking photos where he was not supposed to.
The first question they will ask is if you are calling to report a crime in progress.
True, but irrelevant. My mistake.
The question was how Zimmerman should have taken the police advice, "We don't need you to do that", not which line to the police he was on.