811 Chicago members
| Service Type | Member Agencies | 811 Chicago Site Numbers |
| Electric | City of Chicago | 22 |
| Commonwealth Edison | 4 and 5 | |
| JC Deacux (HBK) | 15 and 202 | |
| Exelon Corporation (ComED) | 60 | |
| Cable/ | AT&T (O'Hara) | 129 |
| Telecommunications | AT&T (SBC IL) | 70 |
| AT&T Local | 11 | |
| AT&T Long Distance | 20 | |
| Comcast Cable | 27 and 29 | |
| Crown Castle | 68 and 208 | |
| DePaul University | 75 | |
| Rogers Telecom/Gabe's Technical Service | 42 and 84 | |
| Job 8 LLC | 71 | |
| Lakeside Tech Center (Digital Realty) | 12 | |
| Level 3 Communications | 36 | |
| Mobilitie LLC | 209 | |
| Century Link | 35 | |
| City of Chicago (COC) | 22 | |
| Cook County Bureau of Technology | 77 | |
| RCN | 34 | |
| Sprint/Nextel | 61 | |
| Sprint | 28 | |
| State of Illinois - CMS | 74 | |
| Sunesys LLC | 156 | |
| Turnkey Networks Solutions (US Signal) | 69 | |
| University of Chicago | 90 | |
| Wide Open West (WOW) | 55 and 203 | |
| XO Communications | 38 | |
| Sidera (Lightower) | 72 | |
| Verizon (MCI) | 24 | |
| Verizon Wireless | 206 | |
| Vinakom Communications | 200 | |
| Windstream (McLeod US) | 31 | |
| ZAYO Group (fna 360 Networks) | 41 | |
| ZAYO Group (fna AboveNet) | 53 | |
| Natural Gas / Pipeline / | BP Pipeline North America | 46 and 92 |
| Steam Pipes | Kinder Morgan Inc - ARGO Terminal Energy Partners | 49 |
| Kinder Morgan Inc - NGPL | 76 | |
| Buckeay Partners LP (Westshore 2) | 66 | |
| Nicor Gas | 16 | |
| Peoples Gas | 78, 79, 136 and 207 | |
| Praxair | 62 | |
| Enterprise Products Operating, LLC (TEPPCO) | 67 | |
| University of Chicago | 90 | |
| Enwave (MDE Thermal) Chicago | 18 | |
| Sewer | Metropolitan Water Reclamation District | 201 |
| Water | City of Chicago | 22 |
Notes:
- The City of Chicago Department of Sewers will not automatically mark - please contact them at 312-747-8117.
- In addition to the member sites listed above the City of Chicago has several 811 Chicago site numbers used for quality assurance (site numbers 65,73 and 205) - there are no facilities connected with these site numbers and the City will not mark or issue positive responses.
Valid as of 04/20/17