313 area code — Detroit, MI geographic

Data: NANPA public reports, current as of July 28, 2026.

Phone numbers beginning 313 are registered to the Detroit area of Michigan (Eastern time zone). The code entered service on January 1, 1947. It is part of the 313/679 overlay complex — these codes share the same territory. Note that porting and VoIP mean a 313 number can be used from anywhere — the code marks where the number was assigned.

763 central-office prefixes are currently active in this code, spread across 35 code-holding carriers. Thousands-block pooling applies to 479 prefixes, so a single prefix can belong to several carriers. Its prefixes map to 6 distinct rate centers.

Practical takeaway: the 313 label narrows geography to Michigan, the prefix narrows it to a locality, and neither authenticates a caller. Verification means calling back through a number you found yourself.

313 was created from 313 in 1947. It has since spawned 313 (1947), 810 (1993), 734 (1997), 679 (2025).

NANPA projects numbering capacity for the 313/679 complex to exhaust in 2Q 2091.

Dialing: 10D locally, 10D to other codes (1+10 digit permissible at each service provider’s discretion.).

Worth noting: 313 is the oldest area code in Michigan, in service since 1947.

Largest localities in 313

FAQ

Why am I getting spam calls from 313 numbers?

Scammers spoof recognizable area codes so calls look local or familiar. A displayed 313 number does not prove the call originated there — see our guide to spotting spoofed calls.

Where is a 313 number from?

313 is assigned to Detroit and surrounding areas of Michigan in the Eastern time zone. The three digits after the area code (the prefix) narrow it down to a rate center.

Is 313 a toll-free number?

No. 313 is a geographic code; calls are billed like any other domestic call. Toll-free codes are 800, 833, 844, 855, 866, 877 and 888.