Ameritech Wisconsin
d/b/a AT&T Wisconsin
Part of the Ameritech Illinois group. 2 OCNs across 2 states · 8,666 blocks combined.
Holding: AT&T Inc
2000 W Att Center Dr, Room 4G33A
Hoffman Estates, IL 60192-5005
AT&T Wisconsin
2001-02-06
2016-01-13
About AT&T Illinois
AT&T Illinois is the Illinois operating company of AT&T Inc., functioning as a Regional Bell Operating Company (RBOC) providing local exchange and related telecommunications services within the state. It primarily serves consumers and businesses with home internet, fiber optic services, and channel services for intrastate connectivity. As part of the former Illinois Bell Telephone Company, it operates within AT&T's broader national footprint, holding state-level Operating Company Numbers (OCNs) and managing thousands of number blocks.
- Parent: AT&T Inc.
- Services: local exchange, fiber internet, channel services
Sources: AT&T Carrier Mills, IL | Home Services, Plans & Availability · AT&T ILLINOIS GUIDEBOOK PART 15 - Channel Services · AT&T in Illinois - Home & Business Services
Toll-free side: Related toll-free RespOrg: AT&T (code BSSB1). View on resporgs.com →
Numbers by age tier
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Carrier website
att.com: opens in a new tab
HQ: Hoffman Estates, IL
Block portfolio at a glance
By age
- Recent (0). Last 18 mo
- Medium (0)
- Old (159)
- Undated (1,862)
Footprint by state
Stronger blue = more blocks issued in that state. ● marks states with activity in the last 18 months.
- Wisconsin WI · 2,021
Top area codes
Bars show total blocks; red overlay is recent.
Block assignments by year
Sister OCNs in the Ameritech Illinois group
Same customer-facing carrier, different state-registered OCN. Combined stats are on the Ameritech Illinois group page.
| OCN | Company name on file | HQ state | Total | Recent |
|---|---|---|---|---|
| 9329 | Ameritech Illinois | IL | 6,645 | · |
Sister OCNs under AT&T Inc
| OCN | Company | Total | Recent |
|---|---|---|---|
| 6534 | New Cingular Wireless PCS LLC - IL | 58,704 | 6,826 |
| 6214 | New Cingular Wireless PCS LLC - GA | 40,046 | 5,473 |
| 6010 | New Cingular Wireless PCS LLC | 38,106 | 3,019 |
| 4036 | New Cingular Wireless PCS LLC - DC | 30,944 | 4,342 |
| 9533 | Southwestern Bell Telephone Company | 26,095 | 0 |
| 9740 | Pacific Bell Telephone Company | 18,541 | 0 |
| 9417 | Bellsouth Telecommunications Inc dba Southern Bell Telephone & Telegraph | 15,734 | 0 |
| 9419 | Bellsouth Telecommunications Inc dba South Central Bell Telephone | 13,075 | 0 |
| 9329 | Ameritech Illinois | 6,645 | 0 |
| 516C | AT&T Enterprises LLC | 5,935 | 113 |
| 9323 | Ameritech Michigan | 5,035 | 0 |
| 9321 | Ameritech Ohio | 4,377 | 0 |