You should call 9-1-1 when you need the immediate response of an emergency service, such as a police officer, an ambulance, or firefighters. Please call 9-1-1 if there is an immediate risk to the safety of people or property (yours or others), or if there is a medical emergency. A 9-1-1 call from a pay phone is free; you do not have to deposit money to make the call.
When the dispatcher answers your call, try to remain calm as you describe the emergency, and give the location where help is needed. Your telephone number is displayed to the dispatcher, so that you can be called back if more information is needed or if the call is interrupted.
If you call 9-1-1 by accident, or if you change your mind about an incident's severity after you dial, please stay on the line until the dispatcher ends the call; do not just hang up. Instead, stay on the phone and explain to the dispatcher that you dialed by mistake and that you do not have an emergency. Otherwise, the dispatcher (not knowing that there is not an emergency) will spend time trying to call you back or may even send emergency responders to you -- and force other 9-1-1 calls to wait in the meantime.