9-1-1 or 911 (usually pronounced "nine-one-one") is the emergency telephone number for the North American Numbering Plan (NANP) and is the emergency number for Police, Fire, Paramedics and Rescue in Arlington Heights. Arlington Heights began 9-1-1 service in August of 1991. The 9-1-1 service is provided by Northwest Central Dispatch System (NWCDS), which is a consolidated, multi-jurisdictional emergency communications system that also serves Buffalo Grove, Elk Grove Village, Hoffman Estates, Mount Prospect, Palatine, Palatine Rural (fire only), Prospect Heights (police only), and Streamwood. "Northwest Central Dispatch" was in operation before 9-1-1 services were available and originally provided emergency service for the police department, with the fire department and emergency medical service (EMS) calls added later.

NWCDS is the MABAS Division 1 (mabas1.org) Dispatch Center that manages communications for major fires, accidents and specialized rescues, such as hazardous materials incidents, underwater rescue/recovery and technical rescues (trench, building collapse, overhead or high angle rescues). These are usually prolonged operations that are managed on a common radio frequency called IFERN (Interagency Fire Emergency Radio Network). IFERN was formerly known as NIFERN (Northern Illinois Fire Emergency Radio Network). MABAS (mabas.org) stands for Mutual Aid Box Alarm System and originated in Arlington Heights and Elk Grove Village in the 1960's so fire departments could use pre-planned coordination of resources to respond to major events. Today MABAS includes over 550 member fire departments in Illinois, Wisconsin and other states.

NWCDS answers over 270,000 calls per year and dispatches about 195,000 police call and about 35,000 fire/EMS calls.

9-1-1 is one of eight N11 codes. In some jurisdictions, the use of this number is reserved for true emergency circumstances only. Currently 9-1-1 is used for all police, fire and EMS calls in Arlington Heights.