How 911 Works

HOW 9-1-1 Works

The idea for 9-1-1 first came about in 1957, when the National Association of Fire Chiefs wanted to establish a nationwide number for people to use to report fires. Over the next decade, various associations, recommendations and congressional debates determined that a single number for reporting all emergencies made more sense than having a different number for each type of emergency. It would be too hard to remember in an instant and so would defeat the purpose. The system's creators choose "9-1-1" for a few of reasons: It's short, it's easy to remember and it was not yet assigned as an area code or any other telephone-related number.

Haleyville, Alabama set up the first 9-1-1 system in the country in 1968. That same year, the second 9-1-1 service popped up in Nome, Alaska.

The idea behind 9-1-1 is pretty simple: Give people a single, easy-to-remember number to call to receive help during any life-threatening situation. There is no national 9-1-1 system. The answering points and corresponding dispatch services are set up and maintained locally, usually by county, often in a joint effort between local government and any phone companies active in the area. You pay for 9-1-1 with your local taxes and through a surcharge on your phone bill.

How Does My Call Get to 9-1-1?

When you call from a phone installed at a residence, business or a pay phone, the phone number of the phone determines which 9-1-1 center you reach. Each 9-1-1 center or Public Safety Answering Point (PSAP) has an enormous list of phone numbers that are designated to come to that center. All of these numbers have a special secondary number on file with the phone company that directs your call to the correct 9-1-1 center for your area.

If you call from a cell phone the procedure is slightly different. Cell phones transmit to the nearest cellular tower and from there to the closest 9-1-1 center. The 9-1-1 center is determined by the location of the cell tower. Sometimes if you are close to a county or state border, you might get the wrong 9-1-1 center. However, the employees there will direct your call to the correct center to get the help you need.

In some locations responses for various types of calls may come from more than one jurisdiction. In those cases you might speak to more than one dispatcher, as each 9-1-1 center involved gathers the information they need.

If you are hearing or speech impaired, most Communications Centers are equipped with a Text Telephone (TTY) device to allow communication through your TTY device.

If you do not speak English, we will contact the Language Line to provide an interpreter. It helps us if you are able to tell us the name of the language you speak in English, so we can tell the Language Line which interpreter to choose.

Once you reach 9-1-1, the dispatcher will ask some questions. If you do have an emergency, the dispatcher will ask questions to determine who to send. Some of these questions will be:

  • What is the address of your emergency? There are ambulances, fire trucks and police officers all over Arapahoe and Douglas Counties. We want to send the ones who are closest and can provide the quickest help. When we ask this question we want to know the address of your emergency, which is not necessarily the address in which you are calling from. We really want an exact address, but sometimes you won't know that. We will ask for cross streets, what kind of building it is, what color is it and other questions to help us find you as quickly as possible.
  • What is the phone number you are calling from? This is important in the event we get disconnected, or in case we need to call you back for further information.
  • Tell me exactly what happened. We will ask specific questions related to the situation. Sometimes responders may need special equipment, and not all vehicles carry the same kind of stuff. We want to send you the right help.

While we ask the questions, we are entering the information into a computerized dispatch system. Other dispatchers can see that information and send help to you while we are still talking to you on the phone. Answering questions does not delay response. We will often keep you on the phone and obtain more information to give the responders. For example, it often helps the paramedics on the ambulance to know what kind of medication the patient takes every day. The patient might be having a breathing problem that is unrelated to the medication, but that information will improve the quality of care the paramedics can provide.