Watch Demetrios Sanders' video report:10-digit dialing to be required as Detroit's 313 area code gets company from 679Starting October 7, customers within the 313 area code will be required to dial 10 digits for all local calls. The change comes as preparation for the introduction of a new 679 area code. The 313 area code has become deeply embedded in Detroit's identity. It's like it's symbolic to Detroit, you think about Detroit, you think about the area code 313," Eric Wright said. PREVIOUS REPORT: Commission likely to approve new 679 area code as iconic 313 phone number combinations begin to run outCommission likely to approve new 679 area code as 313 numbers begin to run outCurrent 313 phone number holders will keep their existing area codes unchanged.