Longtime locals will need to retrain their fingers and businesses possibly will need to reprogram some systems by Sunday, Oct. 24, when 10-digit dialing becomes mandatory for all phone systems in the 970 area code in Colorado.

The move to require 10-digit dialing across multiple states and area codes is part of a Federal Communications Commission change determined in July 2020 that will allow the addition of a nationwide three-digit number — 988 — to reach the National Suicide Prevention Lifeline starting July 16, 2022.

Communication companies are mailing informational postcards to local residents that list other examples where phone numbers might need to be updated or reprogrammed, such as business promotional materials and signs, websites, pet ID tags, voicemail services, speed- and auto-dialers, forwarding settings, fax machines, copiers used for fax services or internet dial-up numbers.

According to the Colorado Department of Regulatory Agencies, a local call will remain a local call regardless of the number of digits dialed. Callers will continue to dial the area code plus the telephone number for long-distance calls.

The gradual changeover began April 24 with a transitional time when consumers could dial seven or 10 digits. Since late April, if a consumer forgot to include the area code, the call was still completed. Starting Sunday, the grace period will end.

According to Colorado Department of Regulatory Agencies officials, 37 states and 83 area codes are impacted by this month’s change to mandatory 10-digit dialing. More information is available at FCC.gov/suicide-prevention-hotline.