Area Code Overview

Area code 773 is a geographic telephone area code in Illinois that went into service on October 12, 1996. The geographic regions covered by this area code overlay has a population of approximately 2,792,539.

Overlay and Dialing Rules

Area Code: 773
State: Illinois
Type: General Purpose Code
In Service Date: October 12, 1996
Overlay Complex: 312/773/872
Local Dialing Plan: This area requires you to dial 1 and the area code when calling locally.

Estimated Number of Assigned Phone Numbers in Area Code 773

This area code is ranked 24th out of 363 nationwide in estimated assigned phone numbers. Within the state territory it serves, it is ranked 2nd out of 16.

6,888,000

Estimated Service-Type Mix of Assigned Phone Numbers in Area Code 773

Total assigned 6,888,000

Wireless

3,486,000 assigned

50.61%

Wireline and VoIP

3,053,000 assigned

44.32%

Other / Unclassified

349,000 assigned

5.07%

Estimated Share of Wireless Numbers Originally Assigned to Each Carrier in Area Code 773

Estimated assigned wireless phone numbers: 3,486,000

Numbers may later be ported to another carrier, but this chart reflects original number assignment, not current subscriber share.

T-Mobile 1,937,000 (55.57%)

AT&T Wireless 929,000 (26.65%)

Verizon Wireless 620,000 (17.79%)

Estimated Share of Wireline and VoIP Numbers Originally Assigned to Each Carrier in Area Code 773

Estimated assigned wireline and VoIP phone numbers: 3,053,000

AT&T 1,877,000 (61.48%)

Bandwidth 300,000 (9.83%)

Onvoy 296,000 (9.70%)

Lumen 164,000 (5.37%)

Comcast Business 108,000 (3.54%)

PAETEC ITEL, LLC 78,000 (2.55%)

Spectrum 75,000 (2.46%)

RCN TELECOM SERVICES OF ILLINIOS, INC. - IL 48,000 (1.57%)

MCIMETRO ACCESS TRANSMISSION SERVICES LLC 38,000 (1.24%)

Peerless Network 36,000 (1.18%)

Telnyx 13,000 (0.43%)

Commio 10,000 (0.33%)

Other / Unclassified Assigned Numbering in Area Code 773

Estimated assigned other or unclassified phone numbers: 349,000

SPOK, INC. 130,000 (37.25%)

FIRST COMMUNICATIONS, LLC 83,000 (23.78%)

AMERICAN MESSAGING SERVICES, LLC 60,000 (17.19%)

INDIANA PAGING NETWORK, INC. 20,000 (5.73%)

ACCESS ONE, INC. - IL 17,000 (4.87%)

TELEPORT COMMUNICATIONS AMERICA, LLC - IL 12,000 (3.44%)

IP HORIZON LLC 10,000 (2.87%)

CLEAR RATE COMMUNICATIONS, LLC 5,000 (1.43%)

STRATUS NETWORKS 4,000 (1.15%)

HD CARRIER LLC 3,000 (0.86%)

FRACTEL, LLC 2,000 (0.57%)

FIVE9, INC. 1,000 (0.29%)

Cities and Towns in Area Code 773

Chicago, Illinois Hinsdale, Illinois La Grange, Illinois Northbrook, Illinois Roselle, Illinois Wheeling, Illinois

These geographic regions are also served by area codes 312 and 872.

How These Figures Were Built

These figures are estimates based on public phone-number assignment records. They are meant to show the likely mix of assigned phone numbers associated with area code 773, not live customer counts.

Some providers may have assigned phone numbers tied to this area code even if they do not actively market or sell service locally. These figures reflect public number-assignment records, not confirmed local service availability.

They also do not reflect number portability at the individual phone-number level, so some numbers may now be used on a different network or by a different provider than the original assignment records suggest.

Population data and locality matching provided by GeoNames.

Last refreshed: April 15, 2026 6:22 pm