Area code

MI

United States geographic area code, in service since 2025-11-07. Part of the 313/679 overlay complex — ten-digit dialing required.

Split from 313. Overlaid with 313 .

Statusin service

Introduced2025-11-07

JurisdictionMI, US

Local dialing10D

Time zoneEastern

Last verified2026-09-17

Utilization 1.8% of assignable prefixes assigned As of 09/17/2026

0%14 of ~792 assignable NXX values (200–999 excl. N11)100%

Prefix-level assignment does not equal number-level exhaustion; thousands-block pooling extends capacity. First assignment on record —, most recent —.

Area codes serve rate-center geographies, not municipal boundaries. “MI” identifies the jurisdiction, not an exact city footprint.

Top assignees

Ranked by assigned prefixes · initial assignee ≠ current carrier

Largest initial assignees in area code 679
Rank	Assignee	Prefixes	Share
01	MULTIPLE OCN LISTING	14	100%

Important: these are initial assignees from NANPA CO-code records — the carrier a prefix was originally assigned to. Because of number portability, the current serving carrier of any individual number may differ.

Change history

Recorded events for this NPA

2023-07-13 NPA 679 to Overlay NPA 313 (Michigan) overlay
2025-11-07Area code 679 entered service (created from 313).

Planning letters & orders

Primary documents

NANPA planning letters for area code 679
Date	Document	Subject
2023-07-13	PL-618 ↗	NPA 679 to Overlay NPA 313 (Michigan)
2000-04-24	PL-227 ↗	Suspension of Relief in the 248, 313 and 734 NPAs (Michigan)
2000-02-01	PL-209 ↗	NPA 947 to Overlay NPA 248 / NPA 679 to Overlay NPA 313 / NPA 278 to Overlay NPA 734 (Michigan)

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