Area code

IL

United States geographic area code, in service since 2009-11-07. Part of the 312/872, 773/872 overlay complex — ten-digit dialing required.

Split from 312.

Statusin service

Introduced2009-11-07

JurisdictionIL, US

Local dialing1+10D

Time zoneCentral

Last verified2026-09-17

Utilization 36.6% of assignable prefixes assigned As of 09/17/2026

0%290 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 2009-08-07, most recent 2026-09-15.

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

Top assignees

Ranked by assigned prefixes · initial assignee ≠ current carrier

Largest initial assignees in area code 872
Rank	Assignee	Prefixes	Share
01	T-MOBILE USA, INC.	66	22.8%
02	ONVOY, LLC	55	19%
03	NEW CINGULAR WIRELESS PCS, LLC - IL	28	9.7%
04	BANDWIDTH.COM CLEC, LLC - IL	19	6.6%
05	TON80 COMMUNICATIONS, LLC	13	4.5%
06	FRACTEL, LLC	11	3.8%
07	MULTIPLE OCN LISTING	9	3.1%
08	CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL	9	3.1%
09	COMMIO, LLC	8	2.8%
10	TELEPORT COMMUNICATIONS AMERICA, LLC - IL	7	2.4%

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

2009-08-10 NPA 872 to Overlay NPA 312 and 773 (Illinois) overlay
2009-11-07Area code 872 entered service (created from 312).

Planning letters & orders

Primary documents

NANPA planning letters for area code 872
Date	Document	Subject
2009-08-10	PL-392 ↗	NPA 872 to Overlay NPA 312 and 773 (Illinois)
2009-06-15	PL-390 ↗	NPA 872 to Overlay NPA 312 and 773 (Illinois)
1999-10-24	PL-195 ↗	NPA 872 to Overlay NPAs 312 and 773 (Illinois)NPA 464 to Overlay NPA 708NPA 331 to Overlay NPA 630

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