Area Code 779 Location

Area code 779 serves Joliet, Illinois, and much of northern Illinois as an overlay to area code 815. This geographic area code supports phone numbers across a wide region that bridges Chicago’s outer suburbs with north-central Illinois. In Joliet—a major city in Will County—you’ll find well-known landmarks like the Rialto Square Theatre, the Old Joliet Prison, and historic Route 66 connections, all reachable with numbers in 779 or 815.

Major communities in the 815/779 overlay include:

• Joliet
• Rockford
• DeKalb
• Kankakee
• Crystal Lake
• McHenry
• Freeport
• Ottawa
• Woodstock
• LaSalle–Peru

Area code 779 was introduced in 2007 to meet growing demand for new phone numbers without changing existing 815 lines. Because 779 is an overlay, 10‑digit dialing is required for local calls, and both wireless and landline numbers use it in the Central Time Zone (CT). It is a standard geographic area code (not toll-free) and works alongside 815, one of Illinois’s original 1947 area codes, which adds a bit of history to every call in the region.

"All area code overlays require 10‑digit dialing." — Federal Communications Commission (FCC)