The FCC adopted an ordinance on July 16, 2020 requiring those who have a telephone number with a 708 area code to include 1 + area code + telephone number for all local and long distance calls. The change will be mandatory as communication providers offer additional mandated services. On and after this date, local calls dialed with only 7-digits may not be completed, and a recording will inform you that your call cannot be completed as dialed. If you get this recording, you must hang up and dial again 1+10 digits (1 + area code + telephone number).
More information regarding the mandatory change comes from the FCC website at https://www.fcc.gov/consumers/guides/ten-digit-dialing.