I don't think it's possible to make an anonymous 911 call unless you're using a public phone. I think this is ok, since 911 is specifically for emergencies and you generally want the police/EMS to know where you are immediately since seconds can count. I think of it a bit like implied consent in first aid: by calling 911 you are inherently consenting for your location to be shared since it is likely you are in some form of distress requiring that information.
You're mentioning things like organized crime reporting, which are not emergencies. In that case, I'd expect someone to talk to someone in the police department in person, or through an intermediary lawyer - not 911.
You're mentioning things like organized crime reporting, which are not emergencies. In that case, I'd expect someone to talk to someone in the police department in person, or through an intermediary lawyer - not 911.
edit: added the implied consent thought