The City of Detroit and its surrounding areas with a 313 area code will be switching to a 10-digit dialing requirement and a new overlay area code starting later this year.
About two years ago, the North American Numbering Plan (NANPA) proposed that the area start using area code 679 as the number combinations with 313 are running out. The MPSC later approved that plan.
The 313 area code coverage includes Detroit, Hamtramck, Highland Park, Allen Park, Dearborn, Dearborn Heights, Ecorse, the Grosse Pointes, Inkster, Lincoln Park, Redford Township, River Rouge, and Taylor.
Because of the low numbers, telephone providers may issue a new overlay code of 679 to new phone customers starting Nov. 7, 2025. When that area code goes into effect, all local calls with a 313 area code will require 10-digit dialing, which means you have to include the area code with each call.
To prepare customers, there will be a six-month "permissive dialing" period starting April 7 to get used to the requirement. During that time, all local calls can be made with either 7 or 10 digits, and all calls that are local will continue to be local even if you dial 10 digits.
Starting Oct. 7, all local calls must use the 10-digit phone number. Calls using only 7 digits will not be completed.
Current 313 area code customers will not have to change their phone number. The new code applies to new phone lines issued once the area code's numbers are exhausted.
Other important to know about the upcoming addition of the 679 area code include:
- Your current telephone number, including the current 313 area code, will not change.
- You will need to dial the area code and telephone number for all local calls, including calls within the same area code.
- You will continue to dial 1 plus the area code and telephone number for all long-distance calls.
- What is a local call now will remain a local call.
- The price of a call, coverage area, or other rates and services will not change due to the overlay.
- You can still dial just three digits to reach 911 and 988. You can also dial three digits to reach 211, 311, 511, and 811 where available.
