LANSING – Phone customers in Michigan’s 313 area code covering Detroit and several of its closest suburbs need to prepare for a new era in which all phone calls require including an area code when dialing a local call, as the region prepares for the new 679 overlay area code that will cover the same communities.

With the 313 area code running low on phone numbers for new customers, telephone service providers may issue a new overlay area code, 679, to new phone customers starting Nov. 7, 2025. When that area code goes into effect, all local calls within the 313 area code will require 10-digit dialing, or including an area code with each call.

To prepare phone customers for the new dialing requirement, a six-month “permissive dialing” period will begin on April 7, 2025, to give customers time to get used to the new dialing requirement. During this period, local calls can be made with either 7 or 10 digits, and all calls that are local will continue to be local even though you dial 10 digits.

Beginning on Oct. 7, 2025, all local calls made within the 313 area code footprint must use 10 digits, including the area code. Calls placed only using 7 digits will not be completed, and callers may receive a recording asking them to disconnect the call and redial using 10 digits.

Starting Nov. 7, 2025, new telephone lines or services may be assigned numbers using the new 679 area code. However, numbers in the new 679 area code will only be assigned to new customers once telephone numbers in the 313 area code have been exhausted. The exhaust date is currently projected to happen in the fourth quarter of 2027, but the timing is subject to change due to telephone numbering demand.

An important note: Current 313 area code customers will not have to change their phone number and will be able to keep the 313 area code. The new 679 area code applies to new phone lines issued once the 313 area code’s numbers are exhausted.

Here are important facts to know about the upcoming addition of the 679 area code:

  • 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.

Phone customers are encouraged to identify your telephone number as a 10-digit number and include the area code when giving the number to friends, family, business associates and customers, and others.

In preparation, phone customers should ensure all services, automatic dialing equipment, applications, software, or other types of equipment are reprogrammed to dial 10 digits if they are currently programmed to dial 7 digits and recognize the new 679 area code as a valid area code. Examples include life-safety systems, fax machines, Internet dial-up numbers, gates, speed dialers, mobile phone contact lists, call forwarding settings, voicemail services, and similar functions. Be sure to check your business stationery, advertising materials, personal checks, and your personal or pet ID tags to ensure the area code is included in your telephone number.

Important safety and security equipment, such as medical alert devices, and alarm and security systems must be programmed to use 10-digit dialing. Many systems operate on 10-digit dialing by default, but some older equipment may still use 7 digits. Please contact your medical alert or security provider if you are not sure whether your equipment needs to be reprogrammed to accommodate the upcoming change to 10-digit local dialing. Any needed reprogramming of alarm and home security equipment must be done between April 7, 2025, and Oct. 7, 2025.

Remember that all local calls must be programmed using 10 digits and add 1 for all long-distance calls.

For additional information, contact your local telephone service provider, or visit the MPSC’s website: www.michigan.gov/mpsc/consumer/telecommunications/numbering.