Do not hang up! Before you hang up, be sure to tell the dispatcher that you have dialed 911 by mistake and that you do not need emergency help!
This is particularly important if you dial from a business phone with several phone lines. Anytime the police dispatcher receives a 911 "hang-up", the caller must be contacted to be sure that no actual emergency exists. If your business has dozens or even hundreds of phone lines, it may be impossible for the dispatcher to determine, who if anyone, needs help, and an officer must then be dispatched to the address.