This numeric designator identifies a specific geographic region within the North American Numbering Plan. Assigned to central Illinois, it facilitates telephone communication by routing calls to the correct local exchange. For example, a telephone number beginning with 217 indicates a subscriber located within this designated zone.
The designation offers several benefits to the region it serves. It allows for direct inward dialing, simplifying communication for businesses and residents alike. Introduced in 1947 as one of the original area codes, its enduring presence reflects the growth and development of telecommunications infrastructure in the region. Its existence enables efficient call routing and management within the telecommunications network.