Verified Nov 1, 2026 · Source: NANPA CO Code Assignment Records
Area code 312 prefixes
784 of the 786 possible NXX blocks are assigned in area code 312 (99.7% of capacity), spread across 8 rate centers and 36 holders. The largest holders are ILLINOIS BELL TEL CO (334 blocks, 42.6%), NEW CINGULAR WIRELESS PCS, LLC - IL (82 blocks, 10.5%), T-MOBILE USA, INC. (64 blocks, 8.2%). Grouped by brand, AT&T accounts for 442 blocks; brand-attributable holders cover 96% of the code, and the rest are CLECs, VoIP wholesalers and regional carriers that trade under their own names. The assignment records here run from 2001-02-14 to 2026-01-29, with 28 blocks handed out in 2001 alone. 413 blocks (53%) are in thousands-block pooling, meaning the block is shared between carriers in 1,000-number lots rather than held whole – which is why a single NXX can serve several carriers at once. 137 were growth assignments – additional blocks to a carrier that had already filled its earlier ones.
784 assigned blocks of 786
8 rate centers
36 holders of record
53% in thousands-block pooling
Largest holders in 312
| Holder of record, as NANPA names it | Brand | Blocks | Share |
|---|---|---|---|
| ILLINOIS BELL TEL CO | AT&T | 334 | 42.6% |
| NEW CINGULAR WIRELESS PCS, LLC - IL | AT&T | 82 | 10.5% |
| T-MOBILE USA, INC. | T-Mobile | 64 | 8.2% |
| CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL | Verizon | 54 | 6.9% |
| MCIMETRO ACCESS TRANSMISSION SERVICES LLC | Verizon | 33 | 4.2% |
| LEVEL 3 COMMUNICATIONS, LLC - IL | Lumen | 33 | 4.2% |
| SPOK, INC. | Spok | 33 | 4.2% |
| TELEPORT COMMUNICATIONS AMERICA, LLC - IL | AT&T | 22 | 2.8% |
| ONVOY, LLC | Onvoy | 20 | 2.6% |
| AMERICAN MESSAGING SERVICES, LLC | American Messaging | 14 | 1.8% |
| PAETEC ITEL, LLC | Windstream | 13 | 1.7% |
| BANDWIDTH.COM CLEC, LLC - IL | Bandwidth | 12 | 1.5% |
Names are printed as they appear in the assignment records, which is the legal entity rather than the brand. Holding a block is not the same as serving the numbers in it: portability moves numbers between carriers and pooling splits a block between several.
Rate centers with their own page
Rate centers where at least three blocks are assigned, excluding the numbered metro zone codes. The remainder are in the full table below.
All 784 assigned blocks
One row per NXX. “Pooled” means carriers draw 1,000-number lots from the block rather than holding all 10,000, so a pooled prefix can belong to several carriers at once. “Not in service” means assigned but not yet open for calls – a caller ID from one of those is necessarily spoofed. The holder column gives the brand where the legal entity maps to one; the full legal names are in the holders table above, exactly as NANPA records them.
| Prefix | Holder of record | Rate center | Assigned | Pooled | In service |
|---|---|---|---|---|---|
| 312-200 | T-Mobile | CHICGOZN01 | 2017-10-02 | yes | yes |
| 312-201 | AT&T | CHICGOZN01 | – | – | yes |
| 312-202 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-203 | AT&T | CHICGOZN01 | – | – | yes |
| 312-204 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-205 | Verizon | CHICGOZN01 | – | – | yes |
| 312-206 | AT&T | CHICGOZN01 | – | – | yes |
| 312-207 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-208 | AT&T | CHICGOZN01 | – | – | yes |
| 312-209 | Verizon | NORTHBROOK | – | yes | yes |
| 312-210 | Peerless | CHICGOZN01 | – | yes | yes |
| 312-212 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-213 | AT&T | CHICGOZN01 | – | – | yes |
| 312-214 | AT&T | CHICGOZN01 | – | – | yes |
| 312-215 | AT&T | WHEELING | – | yes | yes |
| 312-216 | FIRST COMMUNICATIONS, LLC | CHICGOZN01 | 2012-02-13 | yes | yes |
| 312-217 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-218 | AT&T | CHICGOZN01 | – | – | yes |
| 312-219 | Bandwidth | CHICGOZN01 | 2012-04-10 | yes | yes |
| 312-220 | AT&T | CHICGOZN01 | – | – | yes |
| 312-221 | T-Mobile | CHICGOZN01 | 2011-06-17 | yes | yes |
| 312-222 | AT&T | CHICGOZN01 | – | – | yes |
| 312-223 | AT&T | CHICGOZN01 | – | – | yes |
| 312-224 | Lumen | CHICGOZN01 | – | – | yes |
| 312-225 | AT&T | CHICGOZN01 | – | – | yes |
| 312-226 | AT&T | CHICGOZN01 | – | – | yes |
| 312-227 | AT&T | CHICGOZN01 | 2010-09-15 | yes | yes |
| 312-228 | AT&T | CHICGOZN01 | – | – | yes |
| 312-229 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-230 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-231 | AT&T | ROSELLE | – | – | yes |
| 312-232 | American Messaging | CHICGOZN01 | 2001-04-23 | – | yes |
| 312-233 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-234 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-235 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-236 | AT&T | CHICGOZN01 | – | – | yes |
| 312-237 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-238 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-239 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-240 | AT&T | CHICGOZN01 | – | – | yes |
| 312-241 | AT&T | CHICGOZN01 | 2011-08-17 | yes | yes |
| 312-242 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-243 | AT&T | CHICGOZN01 | – | – | yes |
| 312-244 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-245 | AT&T | CHICGOZN01 | – | – | yes |
| 312-246 | AT&T | WHEELING | – | yes | yes |
| 312-247 | FIRST COMMUNICATIONS, LLC | CHICGOZN01 | 2004-04-06 | yes | yes |
| 312-248 | T-Mobile | CHICGOZN01 | 2014-07-01 | yes | yes |
| 312-249 | Spok | CHICGOZN01 | – | – | yes |
| 312-250 | Spok | CHICGOZN01 | – | – | yes |
| 312-251 | AT&T | CHICGOZN01 | – | – | yes |
| 312-252 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-253 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-254 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-255 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-256 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-257 | Verizon | CHICGOZN01 | 2011-08-18 | yes | yes |
| 312-258 | AT&T | CHICGOZN01 | – | – | yes |
| 312-259 | AT&T | CHICGOZN01 | – | – | yes |
| 312-260 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-261 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-262 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-263 | AT&T | CHICGOZN01 | – | – | yes |
| 312-264 | Lumen | CHICGOZN01 | – | – | yes |
| 312-265 | ACCESS ONE, INC. - IL | CHICGOZN01 | 2005-11-29 | yes | yes |
| 312-266 | AT&T | CHICGOZN01 | – | – | yes |
| 312-267 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-268 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-269 | AT&T | CHICGOZN01 | – | – | yes |
| 312-270 | T-Mobile | CHICGOZN01 | 2017-01-16 | yes | yes |
| 312-271 | Spok | CHICGOZN01 | – | – | yes |
| 312-272 | Spok | CHICGOZN01 | – | – | yes |
| 312-273 | Verizon | CHICGOZN01 | 2011-09-13 | yes | yes |
| 312-274 | AT&T | CHICGOZN01 | – | – | yes |
| 312-275 | Verizon | CHICGOZN01 | – | – | yes |
| 312-276 | Verizon | CHICGOZN01 | – | – | yes |
| 312-277 | Verizon | CHICGOZN01 | – | – | yes |
| 312-278 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-279 | Verizon | CHICGOZN01 | – | – | yes |
| 312-280 | AT&T | CHICGOZN01 | – | – | yes |
| 312-281 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-282 | AT&T | CHICGOZN01 | – | – | yes |
| 312-283 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-284 | XO ILLINOIS, INC. | CHICGOZN01 | – | yes | yes |
| 312-285 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-286 | AT&T | CHICGOZN01 | – | – | yes |
| 312-287 | T-Mobile | CHICGOZN07 | – | yes | yes |
| 312-288 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-289 | Spok | CHICGOZN01 | – | – | yes |
| 312-290 | Spok | CHICGOZN01 | – | – | yes |
| 312-291 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-292 | Bandwidth | CHICGOZN01 | 2011-09-02 | yes | yes |
| 312-293 | AT&T | CHICGOZN01 | – | – | yes |
| 312-294 | AT&T | CHICGOZN01 | – | – | yes |
| 312-295 | Spok | LA GRANGE | – | – | yes |
| 312-296 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-297 | AT&T | CHICGOZN01 | – | – | yes |
| 312-298 | RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | CHICGOZN01 | – | yes | yes |
| 312-299 | Spok | CHICGOZN01 | – | – | yes |
| 312-300 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-301 | AT&T | HINSDALE | – | – | yes |
| 312-302 | AT&T | CHICGOZN01 | – | – | yes |
| 312-303 | AT&T | WHEELING | – | yes | yes |
| 312-304 | AT&T | HINSDALE | – | yes | yes |
| 312-305 | Verizon | NORTHBROOK | – | yes | yes |
| 312-306 | AT&T | CHICGOZN01 | – | – | yes |
| 312-307 | AT&T | CHICGOZN01 | – | – | yes |
| 312-308 | AT&T | CHICGOZN01 | – | – | yes |
| 312-309 | AT&T | CHICGOZN01 | – | – | yes |
| 312-310 | Verizon | NORTHBROOK | – | yes | yes |
| 312-312 | Onvoy | CHICGOZN01 | 2018-01-19 | yes | yes |
| 312-313 | Onvoy | CHICGOZN01 | 2014-11-10 | yes | yes |
| 312-314 | AT&T | HINSDALE | – | yes | yes |
| 312-315 | AT&T | CHICGOZN01 | – | – | yes |
| 312-316 | AT&T | CHICGOZN01 | – | – | yes |
| 312-317 | AT&T | WHEELING | – | yes | yes |
| 312-318 | Verizon | LA GRANGE | – | yes | yes |
| 312-319 | Verizon | CHICGOZN01 | 2017-04-28 | yes | yes |
| 312-320 | AT&T | CHICGOZN01 | – | – | yes |
| 312-321 | AT&T | CHICGOZN01 | – | – | yes |
| 312-322 | AT&T | CHICGOZN01 | – | – | yes |
| 312-323 | American Messaging | CHICGOZN01 | 2001-04-13 | – | yes |
| 312-324 | Lumen | CHICGOZN01 | 2001-05-03 | yes | yes |
| 312-325 | AT&T | CHICGOZN01 | 2003-06-24 | yes | yes |
| 312-326 | AT&T | CHICGOZN01 | – | – | yes |
| 312-327 | Verizon | CHICGOZN01 | – | – | yes |
| 312-328 | AT&T | CHICGOZN01 | – | – | yes |
| 312-329 | AT&T | CHICGOZN01 | – | – | yes |
| 312-330 | AT&T | CHICGOZN01 | – | – | yes |
| 312-331 | AT&T | WHEELING | – | yes | yes |
| 312-332 | AT&T | CHICGOZN01 | – | – | yes |
| 312-333 | American Messaging | CHICGOZN01 | 2001-04-13 | – | yes |
| 312-334 | FIRST COMMUNICATIONS, LLC | CHICGOZN01 | – | – | yes |
| 312-335 | AT&T | CHICGOZN01 | – | – | yes |
| 312-336 | AT&T | CHICGOZN01 | – | – | yes |
| 312-337 | AT&T | CHICGOZN01 | – | – | yes |
| 312-338 | AT&T | CHICGOZN01 | – | – | yes |
| 312-339 | Verizon | CHICGOZN01 | – | – | yes |
| 312-340 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-341 | AT&T | CHICGOZN01 | – | – | yes |
| 312-342 | AT&T | CHICGOZN01 | – | – | yes |
| 312-343 | Verizon | CHICGOZN01 | – | – | yes |
| 312-344 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-345 | AT&T | CHICGOZN01 | – | – | yes |
| 312-346 | AT&T | CHICGOZN01 | – | – | yes |
| 312-347 | AT&T | CHICGOZN01 | – | – | yes |
| 312-348 | Onvoy | CHICGOZN01 | 2003-11-14 | yes | yes |
| 312-349 | Spok | CHICGOZN01 | – | – | yes |
| 312-350 | Verizon | CHICGOZN01 | – | – | yes |
| 312-351 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-352 | AT&T | HINSDALE | – | yes | yes |
| 312-353 | AT&T | CHICGOZN01 | – | – | yes |
| 312-354 | AT&T | ROSELLE | – | yes | yes |
| 312-355 | AT&T | CHICGOZN01 | – | – | yes |
| 312-356 | AT&T | CHICGOZN01 | – | – | yes |
| 312-357 | AT&T | CHICGOZN01 | – | – | yes |
| 312-358 | T-Mobile | CHICGOZN01 | 2015-07-21 | yes | yes |
| 312-359 | Spok | CHICGOZN01 | – | – | yes |
| 312-360 | AT&T | CHICGOZN01 | – | – | yes |
| 312-361 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-362 | AT&T | CHICGOZN01 | – | – | yes |
| 312-363 | RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | CHICGOZN01 | – | yes | yes |
| 312-364 | AT&T | CHICGOZN01 | – | – | yes |
| 312-365 | Spok | CHICGOZN01 | – | – | yes |
| 312-366 | AT&T | CHICGOZN01 | 2016-02-03 | yes | yes |
| 312-367 | Spok | LA GRANGE | – | – | yes |
| 312-368 | AT&T | CHICGOZN01 | – | – | yes |
| 312-369 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-370 | Spok | CHICGOZN01 | – | – | yes |
| 312-371 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-372 | AT&T | CHICGOZN01 | – | – | yes |
| 312-373 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-374 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-375 | T-Mobile | CHICGOZN01 | – | – | yes |
| 312-376 | Onvoy | CHICGOZN01 | – | yes | yes |
| 312-377 | Verizon | CHICGOZN01 | – | – | yes |
| 312-378 | Spok | CHICGOZN01 | – | – | yes |
| 312-379 | Windstream | CHICGOZN01 | 2001-04-10 | yes | yes |
| 312-380 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-381 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-382 | AT&T | CHICGOZN01 | – | – | yes |
| 312-383 | AT&T | CHICGOZN01 | 2016-02-01 | yes | yes |
| 312-384 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-385 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-386 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-387 | Spok | CHICGOZN01 | – | – | yes |
| 312-388 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-389 | Spok | CHICGOZN01 | – | – | yes |
| 312-390 | American Messaging | CHICGOZN01 | 2001-04-16 | – | yes |
| 312-391 | AT&T | CHICGOZN01 | – | – | yes |
| 312-392 | Onvoy | CHICGOZN01 | 2017-10-23 | yes | yes |
| 312-393 | American Messaging | CHICGOZN01 | 2001-04-23 | – | yes |
| 312-394 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-395 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-396 | AT&T | CHICGOZN01 | – | – | yes |
| 312-397 | AT&T | CHICGOZN01 | – | – | yes |
| 312-398 | Spok | CHICGOZN01 | – | – | yes |
| 312-399 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-400 | American Messaging | CHICGOZN01 | 2001-04-13 | – | yes |
| 312-401 | AT&T | CHICGOZN01 | – | – | yes |
| 312-402 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-403 | Verizon | LA GRANGE | – | yes | yes |
| 312-404 | T-Mobile | CHICGOZN01 | 2002-10-14 | – | yes |
| 312-405 | Verizon | CHICGOZN01 | – | – | yes |
| 312-406 | AT&T | WHEELING | – | yes | yes |
| 312-407 | AT&T | CHICGOZN01 | – | – | yes |
| 312-408 | AT&T | CHICGOZN01 | – | – | yes |
| 312-409 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-410 | AT&T | CHICGOZN01 | – | – | yes |
| 312-412 | AT&T | WHEELING | – | yes | yes |
| 312-413 | AT&T | CHICGOZN01 | – | – | yes |
| 312-414 | Vonage | CHICGOZN01 | 2016-08-12 | yes | yes |
| 312-415 | Verizon | CHICGOZN01 | – | – | yes |
| 312-416 | Verizon | CHICGOZN01 | – | – | yes |
| 312-417 | AT&T | CHICGOZN01 | – | – | yes |
| 312-418 | Spok | CHICGOZN01 | – | – | yes |
| 312-419 | AT&T | CHICGOZN01 | – | – | yes |
| 312-420 | AT&T | CHICGOZN01 | – | – | yes |
| 312-421 | AT&T | CHICGOZN01 | – | – | yes |
| 312-422 | AT&T | CHICGOZN01 | – | – | yes |
| 312-423 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-424 | AT&T | CHICGOZN01 | – | – | yes |
| 312-425 | AT&T | CHICGOZN01 | – | – | yes |
| 312-426 | Onvoy | CHICGOZN01 | 2026-01-27 | yes | yes |
| 312-427 | AT&T | CHICGOZN01 | – | – | yes |
| 312-428 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-429 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-430 | AT&T | CHICGOZN01 | – | – | yes |
| 312-431 | AT&T | CHICGOZN01 | – | – | yes |
| 312-432 | AT&T | CHICGOZN01 | – | – | yes |
| 312-433 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-434 | T-Mobile | CHICGOZN01 | 2011-07-08 | yes | yes |
| 312-435 | AT&T | CHICGOZN01 | – | – | yes |
| 312-436 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-437 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-438 | Verizon | CHICGOZN01 | 2017-06-02 | yes | yes |
| 312-439 | AT&T | CHICGOZN01 | 2016-11-28 | yes | yes |
| 312-440 | AT&T | CHICGOZN01 | – | – | yes |
| 312-441 | AT&T | CHICGOZN01 | – | – | yes |
| 312-442 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-443 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-444 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-445 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-446 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-447 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-448 | Verizon | CHICGOZN01 | 2011-08-02 | yes | yes |
| 312-449 | WAVENATION, LLC | CHICGOZN01 | 2025-07-21 | yes | yes |
| 312-450 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-451 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-452 | Charter | CHICGOZN01 | 2025-09-02 | yes | yes |
| 312-453 | Verizon | CHICGOZN01 | – | – | yes |
| 312-454 | AT&T | CHICGOZN01 | – | – | yes |
| 312-455 | AT&T | CHICGOZN01 | – | – | yes |
| 312-456 | AT&T | CHICGOZN01 | – | – | yes |
| 312-457 | American Messaging | CHICGOZN01 | 2001-04-23 | – | yes |
| 312-458 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-459 | T-Mobile | CHICGOZN01 | 2011-08-02 | yes | yes |
| 312-460 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-461 | AT&T | CHICGOZN01 | – | – | yes |
| 312-462 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-463 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-464 | AT&T | CHICGOZN01 | – | – | yes |
| 312-465 | Windstream | CHICGOZN01 | 2009-03-26 | yes | yes |
| 312-466 | AT&T | CHICGOZN01 | – | – | yes |
| 312-467 | AT&T | CHICGOZN01 | – | – | yes |
| 312-468 | T-Mobile | CHICGOZN01 | 2015-06-26 | yes | yes |
| 312-469 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-470 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-471 | Verizon | CHICGOZN01 | 2015-06-26 | yes | yes |
| 312-472 | AT&T | CHICGOZN01 | 2005-10-27 | yes | yes |
| 312-473 | Onvoy | CHICGOZN01 | 2006-11-15 | yes | yes |
| 312-474 | AT&T | CHICGOZN01 | – | – | yes |
| 312-475 | AT&T | CHICGOZN01 | – | – | yes |
| 312-476 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-477 | Lumen | CHICGOZN01 | 2010-10-20 | yes | yes |
| 312-478 | T-Mobile | CHICGOZN01 | 2014-03-20 | yes | yes |
| 312-479 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-480 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-481 | T-Mobile | CHICGOZN01 | 2017-07-07 | yes | yes |
| 312-482 | AT&T | CHICGOZN01 | – | – | yes |
| 312-483 | T-Mobile | CHICGOZN01 | 2014-08-22 | yes | yes |
| 312-484 | Spok | CHICGOZN01 | – | – | yes |
| 312-485 | Verizon | CHICGOZN01 | – | – | yes |
| 312-486 | Verizon | CHICGOZN01 | 2004-04-23 | yes | yes |
| 312-487 | T-Mobile | CHICGOZN01 | 2014-10-27 | yes | yes |
| 312-488 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-489 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-490 | Spok | CHICGOZN01 | – | – | yes |
| 312-491 | AT&T | CHICGOZN01 | – | – | yes |
| 312-492 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-493 | T-Mobile | CHICGOZN01 | – | – | yes |
| 312-494 | AT&T | CHICGOZN01 | – | – | yes |
| 312-495 | Spok | CHICGOZN01 | – | – | yes |
| 312-496 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-497 | Verizon | CHICGOZN01 | – | – | yes |
| 312-498 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-499 | AT&T | CHICGOZN01 | – | – | yes |
| 312-500 | Onvoy | CHICGOZN01 | 2018-05-22 | yes | yes |
| 312-501 | Verizon | LA GRANGE | – | yes | yes |
| 312-502 | Verizon | CHICGOZN01 | – | – | yes |
| 312-503 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-504 | AT&T | CHICGOZN01 | – | – | yes |
| 312-505 | Verizon | CHICGOZN01 | – | – | yes |
| 312-506 | FIRST COMMUNICATIONS, LLC | CHICGOZN01 | 2004-05-24 | yes | yes |
| 312-507 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-508 | Peerless | CHICGOZN01 | 2012-03-19 | yes | yes |
| 312-509 | Peerless | CHICGOZN01 | 2012-03-06 | yes | yes |
| 312-510 | AT&T | HINSDALE | – | yes | yes |
| 312-512 | Spok | CHICGOZN01 | – | – | yes |
| 312-513 | AT&T | CHICGOZN01 | – | – | yes |
| 312-514 | American Messaging | CHICGOZN01 | 2001-04-13 | – | yes |
| 312-515 | Verizon | CHICGOZN01 | – | – | yes |
| 312-516 | AT&T | CHICGOZN01 | – | – | yes |
| 312-517 | Verizon | CHICGOZN01 | 2015-02-09 | yes | yes |
| 312-518 | AT&T | WHEELING | – | yes | yes |
| 312-519 | Verizon | CHICGOZN01 | – | – | yes |
| 312-520 | Verizon | CHICGOZN01 | – | – | yes |
| 312-521 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-522 | T-Mobile | CHICGOZN01 | 2014-08-22 | yes | yes |
| 312-523 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-524 | AT&T | WHEELING | – | yes | yes |
| 312-525 | Verizon | CHICGOZN01 | 2002-03-20 | yes | yes |
| 312-526 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-527 | AT&T | CHICGOZN01 | – | – | yes |
| 312-528 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-529 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-530 | STRATUS NETWORKS | CHICGOZN01 | 2020-07-28 | yes | yes |
| 312-531 | AT&T | HINSDALE | – | yes | yes |
| 312-532 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-533 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-534 | AT&T | CHICGOZN01 | 2008-09-17 | yes | yes |
| 312-535 | Bandwidth | CHICGOZN01 | 2017-07-20 | yes | yes |
| 312-536 | T-Mobile | CHICGOZN01 | 2015-06-26 | yes | yes |
| 312-537 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-538 | T-Mobile | CHICGOZN01 | 2017-07-21 | yes | yes |
| 312-539 | T-Mobile | CHICGOZN01 | 2016-01-11 | yes | yes |
| 312-540 | AT&T | CHICGOZN01 | – | – | yes |
| 312-541 | AT&T | CHICGOZN01 | – | – | yes |
| 312-542 | AT&T | CHICGOZN01 | – | – | yes |
| 312-543 | AT&T | CHICGOZN01 | – | – | yes |
| 312-544 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-545 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-546 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-547 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-548 | Lumen | CHICGOZN01 | 2007-09-05 | yes | yes |
| 312-549 | AT&T | CHICGOZN01 | 2015-09-25 | yes | yes |
| 312-550 | Verizon | CHICGOZN01 | – | – | yes |
| 312-551 | AT&T | CHICGOZN01 | – | – | yes |
| 312-552 | AT&T | CHICGOZN01 | – | – | yes |
| 312-553 | AT&T | CHICGOZN01 | – | – | yes |
| 312-554 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-556 | AT&T | CHICGOZN01 | – | – | yes |
| 312-557 | AT&T | CHICGOZN01 | – | – | yes |
| 312-558 | AT&T | CHICGOZN01 | – | – | yes |
| 312-559 | AT&T | CHICGOZN01 | – | – | yes |
| 312-560 | AT&T | CHICGOZN01 | – | – | yes |
| 312-561 | Verizon | CHICGOZN01 | 2012-06-20 | yes | yes |
| 312-562 | Spok | CHICGOZN01 | – | – | yes |
| 312-563 | AT&T | CHICGOZN01 | – | – | yes |
| 312-564 | FIRST COMMUNICATIONS, LLC | CHICGOZN01 | 2006-11-13 | yes | yes |
| 312-565 | AT&T | CHICGOZN01 | – | – | yes |
| 312-566 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-567 | AT&T | CHICGOZN01 | – | – | yes |
| 312-568 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-569 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-570 | AT&T | CHICGOZN01 | – | – | yes |
| 312-571 | Spok | CHICGOZN01 | – | – | yes |
| 312-572 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-573 | AT&T | CHICGOZN01 | – | – | yes |
| 312-574 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-575 | AT&T | CHICGOZN01 | – | – | yes |
| 312-576 | AT&T | CHICGOZN01 | – | – | yes |
| 312-577 | Verizon | CHICGOZN01 | – | – | yes |
| 312-578 | AT&T | CHICGOZN01 | – | – | yes |
| 312-579 | Verizon | CHICGOZN01 | 2017-07-25 | yes | yes |
| 312-580 | AT&T | CHICGOZN01 | – | – | yes |
| 312-581 | AT&T | CHICGOZN01 | 2017-07-31 | yes | yes |
| 312-582 | AT&T | CHICGOZN01 | 2002-05-16 | yes | yes |
| 312-583 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-584 | VoIP Innovations | CHICGOZN01 | 2018-08-14 | yes | yes |
| 312-585 | Verizon | CHICGOZN01 | 2013-04-16 | yes | yes |
| 312-586 | Onvoy | CHICGOZN01 | 2016-05-04 | yes | yes |
| 312-587 | AT&T | CHICGOZN01 | – | – | yes |
| 312-588 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-589 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-590 | Verizon | CHICGOZN01 | – | – | yes |
| 312-591 | AT&T | CHICGOZN01 | – | – | yes |
| 312-592 | AT&T | CHICGOZN01 | – | – | yes |
| 312-593 | T-Mobile | CHICGOZN01 | – | – | yes |
| 312-594 | Verizon | CHICGOZN01 | 2008-11-06 | yes | yes |
| 312-595 | AT&T | CHICGOZN01 | – | – | yes |
| 312-596 | AT&T | CHICGOZN01 | – | – | yes |
| 312-597 | Verizon | CHICGOZN01 | 2016-10-04 | yes | yes |
| 312-598 | Onvoy | CHICGOZN01 | 2019-01-24 | yes | yes |
| 312-599 | Verizon | CHICGOZN01 | 2016-11-21 | yes | yes |
| 312-600 | Onvoy | CHICGOZN01 | 2012-05-01 | yes | yes |
| 312-601 | Verizon | CHICGOZN01 | – | – | yes |
| 312-602 | Lumen | CHICGOZN01 | – | – | yes |
| 312-603 | AT&T | CHICGOZN01 | – | – | yes |
| 312-604 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-605 | Windstream | CHICGOZN01 | 2012-08-06 | yes | yes |
| 312-606 | AT&T | CHICGOZN01 | – | – | yes |
| 312-607 | AT&T | CHICGOZN01 | – | – | yes |
| 312-608 | AT&T | CHICGOZN01 | – | – | yes |
| 312-609 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-610 | Verizon | CHICGOZN01 | 2012-08-06 | yes | yes |
| 312-612 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-613 | AT&T | CHICGOZN01 | – | – | yes |
| 312-614 | AT&T | CHICGOZN01 | 2012-10-19 | yes | yes |
| 312-615 | AT&T | WHEELING | – | yes | yes |
| 312-616 | AT&T | CHICGOZN01 | – | – | yes |
| 312-617 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-618 | AT&T | CHICGOZN01 | – | – | yes |
| 312-619 | T-Mobile | CHICGOZN01 | 2012-09-11 | yes | yes |
| 312-620 | Bandwidth | CHICGOZN01 | 2012-08-15 | yes | yes |
| 312-621 | AT&T | CHICGOZN01 | – | – | yes |
| 312-622 | AT&T | CHICGOZN01 | 2001-02-14 | yes | yes |
| 312-623 | AT&T | CHICGOZN01 | – | – | yes |
| 312-624 | RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | CHICGOZN01 | – | yes | yes |
| 312-625 | Lumen | CHICGOZN01 | 2001-11-12 | yes | yes |
| 312-626 | Onvoy | CHICGOZN01 | 2008-02-04 | yes | yes |
| 312-627 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-628 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-629 | AT&T | CHICGOZN01 | – | – | yes |
| 312-630 | AT&T | CHICGOZN01 | – | – | yes |
| 312-631 | Lumen | CHICGOZN01 | 2013-01-11 | yes | yes |
| 312-632 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-633 | AT&T | CHICGOZN01 | – | – | yes |
| 312-634 | AT&T | CHICGOZN01 | – | – | yes |
| 312-635 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-636 | Verizon | CHICGOZN01 | – | – | yes |
| 312-637 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-638 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-639 | Verizon | CHICGOZN01 | 2017-10-19 | yes | yes |
| 312-640 | AT&T | CHICGOZN01 | – | – | yes |
| 312-641 | AT&T | CHICGOZN01 | – | – | yes |
| 312-642 | AT&T | CHICGOZN01 | – | – | yes |
| 312-643 | RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | CHICGOZN01 | – | – | yes |
| 312-644 | AT&T | CHICGOZN01 | – | – | yes |
| 312-645 | AT&T | CHICGOZN01 | – | – | yes |
| 312-646 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-647 | T-Mobile | CHICGOZN01 | 2013-05-24 | yes | yes |
| 312-648 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-649 | AT&T | CHICGOZN01 | – | – | yes |
| 312-650 | RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | CHICGOZN01 | – | yes | yes |
| 312-651 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-652 | AT&T | CHICGOZN01 | – | – | yes |
| 312-653 | AT&T | CHICGOZN01 | – | – | yes |
| 312-654 | AT&T | CHICGOZN01 | – | – | yes |
| 312-655 | AT&T | CHICGOZN01 | – | – | yes |
| 312-656 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-657 | Spok | CHICGOZN01 | – | – | yes |
| 312-658 | AT&T | CHICGOZN01 | – | – | yes |
| 312-659 | AT&T | CHICGOZN01 | – | – | yes |
| 312-660 | AT&T | CHICGOZN01 | – | – | yes |
| 312-661 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-662 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-663 | AT&T | CHICGOZN01 | – | – | yes |
| 312-664 | AT&T | CHICGOZN01 | – | – | yes |
| 312-665 | AT&T | CHICGOZN01 | – | – | yes |
| 312-666 | AT&T | CHICGOZN01 | – | – | yes |
| 312-667 | Peerless | CHICGOZN01 | 2012-08-31 | yes | yes |
| 312-668 | CSC WIRELESS, LLC | CHICGOZN01 | 2019-05-28 | yes | yes |
| 312-669 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-670 | AT&T | CHICGOZN01 | – | – | yes |
| 312-671 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-672 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-673 | FIRST COMMUNICATIONS, LLC | CHICGOZN01 | – | – | yes |
| 312-674 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-675 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-676 | FIRST COMMUNICATIONS, LLC | CHICGOZN01 | 2006-06-16 | yes | yes |
| 312-677 | Spok | CHICGOZN01 | – | – | yes |
| 312-678 | T-Mobile | CHICGOZN01 | 2013-07-25 | yes | yes |
| 312-679 | TPx | CHICGOZN01 | 2026-01-29 | yes | yes |
| 312-680 | Onvoy | CHICGOZN01 | 2022-04-29 | yes | yes |
| 312-681 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-682 | NUSO, LLC | CHICGOZN01 | 2020-05-14 | yes | yes |
| 312-683 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-684 | T-Mobile | CHICGOZN01 | 2016-09-13 | yes | yes |
| 312-685 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-686 | Peerless | CHICGOZN01 | – | yes | yes |
| 312-687 | T-Mobile | CHICGOZN01 | 2016-09-13 | yes | yes |
| 312-688 | Spok | CHICGOZN01 | – | – | yes |
| 312-689 | American Messaging | CHICGOZN01 | 2001-04-13 | – | yes |
| 312-690 | Lumen | CHICGOZN01 | 2014-05-06 | yes | yes |
| 312-691 | INDIANA PAGING NETWORK, INC. | CHICGOZN01 | – | – | yes |
| 312-692 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-693 | AT&T | CHICGOZN01 | – | – | yes |
| 312-694 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-695 | AT&T | CHICGOZN01 | – | – | yes |
| 312-696 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-697 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-698 | Lumen | CHICGOZN01 | 2001-08-23 | yes | yes |
| 312-699 | AT&T | HINSDALE | – | yes | yes |
| 312-701 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-702 | Verizon | CHICGOZN01 | 2012-12-31 | yes | yes |
| 312-703 | AT&T | CHICGOZN01 | – | – | yes |
| 312-704 | AT&T | CHICGOZN01 | – | – | yes |
| 312-705 | AT&T | CHICGOZN01 | – | – | yes |
| 312-706 | AT&T | CHICGOZN01 | – | – | yes |
| 312-707 | AT&T | CHICGOZN01 | – | – | yes |
| 312-708 | Charter | CHICGOZN01 | 2024-02-20 | yes | yes |
| 312-709 | T-Mobile | CHICGOZN01 | 2013-05-24 | yes | yes |
| 312-710 | AT&T | CHICGOZN01 | – | – | yes |
| 312-712 | AT&T | CHICGOZN01 | – | – | yes |
| 312-713 | American Messaging | CHICGOZN01 | 2001-04-16 | – | yes |
| 312-714 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-715 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-716 | AT&T | CHICGOZN01 | – | – | yes |
| 312-717 | Spok | LA GRANGE | – | – | yes |
| 312-718 | Verizon | CHICGOZN01 | – | – | yes |
| 312-719 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-720 | Verizon | CHICGOZN01 | – | – | yes |
| 312-721 | T-Mobile | CHICGOZN01 | 2013-10-22 | yes | yes |
| 312-722 | Windstream | CHICGOZN01 | 2015-06-01 | yes | yes |
| 312-723 | AT&T | CHICGOZN01 | 2016-11-28 | yes | yes |
| 312-724 | Bandwidth | CHICGOZN01 | 2013-02-07 | yes | yes |
| 312-725 | Bandwidth | CHICGOZN01 | 2008-10-08 | yes | yes |
| 312-726 | AT&T | CHICGOZN01 | – | – | yes |
| 312-727 | AT&T | CHICGOZN01 | – | – | yes |
| 312-728 | Verizon | CHICGOZN01 | 2017-10-19 | yes | yes |
| 312-729 | AT&T | CHICGOZN01 | – | – | yes |
| 312-730 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-731 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-732 | AT&T | CHICGOZN01 | – | – | yes |
| 312-733 | AT&T | CHICGOZN01 | – | – | yes |
| 312-734 | AT&T | CHICGOZN01 | 2015-09-17 | yes | yes |
| 312-735 | T-Mobile | CHICGOZN04 | 2001-07-06 | yes | yes |
| 312-736 | AT&T | CHICGOZN01 | 2017-10-20 | yes | yes |
| 312-737 | AT&T | CHICGOZN01 | – | – | yes |
| 312-738 | AT&T | CHICGOZN01 | – | – | yes |
| 312-739 | AT&T | CHICGOZN01 | – | – | yes |
| 312-740 | American Messaging | CHICGOZN01 | 2001-04-13 | – | yes |
| 312-741 | Windstream | CHICGOZN01 | 2017-10-20 | yes | yes |
| 312-742 | AT&T | CHICGOZN01 | – | – | yes |
| 312-743 | AT&T | CHICGOZN01 | 2001-11-15 | yes | yes |
| 312-744 | AT&T | CHICGOZN01 | – | – | yes |
| 312-745 | AT&T | CHICGOZN01 | – | – | yes |
| 312-746 | AT&T | CHICGOZN01 | – | – | yes |
| 312-747 | AT&T | CHICGOZN01 | – | – | yes |
| 312-748 | Onvoy | CHICGOZN01 | 2023-05-22 | yes | yes |
| 312-749 | AT&T | HINSDALE | – | yes | yes |
| 312-750 | AT&T | CHICGOZN01 | – | – | yes |
| 312-751 | AT&T | CHICGOZN01 | – | – | yes |
| 312-752 | Lumen | CHICGOZN01 | 2002-04-19 | yes | yes |
| 312-753 | RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | CHICGOZN01 | – | yes | yes |
| 312-754 | Lumen | CHICGOZN01 | 2013-02-26 | yes | yes |
| 312-755 | AT&T | CHICGOZN01 | – | – | yes |
| 312-756 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-757 | Bandwidth | CHICGOZN01 | – | yes | yes |
| 312-758 | Verizon | CHICGOZN01 | – | – | yes |
| 312-759 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-760 | American Messaging | CHICGOZN01 | 2001-04-13 | – | yes |
| 312-761 | TELENGY LLC | CHICGOZN01 | 2018-05-25 | yes | yes |
| 312-762 | AT&T | CHICGOZN01 | – | – | yes |
| 312-763 | Comcast | CHICGOZN01 | 2014-05-12 | yes | yes |
| 312-764 | AT&T | CHICGOZN01 | 2016-10-20 | yes | yes |
| 312-765 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-766 | Peerless | CHICGOZN01 | 2016-10-17 | yes | yes |
| 312-767 | Bandwidth | CHICGOZN01 | 2015-04-16 | yes | yes |
| 312-768 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-769 | INDIANA PAGING NETWORK, INC. | CHICGOZN01 | – | – | yes |
| 312-770 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-771 | Verizon | CHICGOZN01 | – | – | yes |
| 312-772 | AT&T | CHICGOZN01 | 2008-08-18 | yes | yes |
| 312-773 | Charter | CHICGOZN01 | 2023-05-19 | yes | yes |
| 312-774 | T-Mobile | CHICGOZN01 | 2013-08-19 | yes | yes |
| 312-775 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-776 | T-Mobile | CHICGOZN01 | 2019-01-30 | yes | yes |
| 312-777 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-778 | Onvoy | CHICGOZN01 | 2015-05-08 | yes | yes |
| 312-779 | Onvoy | CHICGOZN01 | 2019-05-13 | yes | yes |
| 312-780 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-781 | AT&T | CHICGOZN01 | – | – | yes |
| 312-782 | AT&T | CHICGOZN01 | – | – | yes |
| 312-783 | AT&T | CHICGOZN01 | 2016-08-08 | yes | yes |
| 312-784 | FIRST COMMUNICATIONS, LLC | CHICGOZN01 | 2007-07-12 | yes | yes |
| 312-785 | AT&T | CHICGOZN01 | 2014-08-19 | yes | yes |
| 312-786 | AT&T | CHICGOZN01 | – | – | yes |
| 312-787 | AT&T | CHICGOZN01 | – | – | yes |
| 312-788 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-789 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-790 | AT&T | CHICGOZN01 | – | – | yes |
| 312-791 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-792 | Verizon | CHICGOZN01 | 2014-11-20 | yes | yes |
| 312-793 | AT&T | CHICGOZN01 | – | – | yes |
| 312-794 | RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | CHICGOZN01 | – | yes | yes |
| 312-795 | AT&T | CHICGOZN01 | – | – | yes |
| 312-796 | Peerless | CHICGOZN01 | 2016-07-26 | yes | yes |
| 312-797 | AT&T | CHICGOZN01 | – | – | yes |
| 312-798 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-799 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-800 | Peerless | CHICGOZN01 | 2012-11-20 | yes | yes |
| 312-801 | NUSO, LLC | CHICGOZN01 | 2013-04-29 | yes | yes |
| 312-802 | Verizon | CHICGOZN01 | – | – | yes |
| 312-803 | Verizon | CHICGOZN01 | – | – | yes |
| 312-804 | T-Mobile | CHICGOZN01 | 2002-01-23 | – | yes |
| 312-805 | Verizon | CHICGOZN01 | – | – | yes |
| 312-806 | AT&T | CHICGOZN01 | – | – | yes |
| 312-807 | AT&T | CHICGOZN01 | – | – | yes |
| 312-808 | AT&T | CHICGOZN01 | – | – | yes |
| 312-809 | Verizon | CHICGOZN01 | 2013-10-25 | yes | yes |
| 312-810 | AT&T | CHICGOZN01 | – | – | yes |
| 312-812 | AT&T | CHICGOZN01 | – | – | yes |
| 312-813 | AT&T | CHICGOZN01 | – | – | yes |
| 312-814 | AT&T | CHICGOZN01 | – | – | yes |
| 312-815 | AIRESPRING, INC. | CHICGOZN01 | 2018-05-07 | yes | yes |
| 312-816 | AT&T | HINSDALE | – | yes | yes |
| 312-817 | AT&T | CHICGOZN01 | – | – | yes |
| 312-818 | T-Mobile | CHICGOZN01 | 2013-08-19 | yes | yes |
| 312-819 | AT&T | CHICGOZN01 | – | – | yes |
| 312-820 | Onvoy | CHICGOZN01 | 2020-01-08 | yes | yes |
| 312-821 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-822 | AT&T | CHICGOZN01 | – | – | yes |
| 312-823 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-824 | Verizon | CHICGOZN01 | 2016-06-20 | yes | yes |
| 312-825 | T-Mobile | CHICGOZN01 | 2016-03-17 | yes | yes |
| 312-826 | T-Mobile | CHICGOZN01 | 2016-06-17 | yes | yes |
| 312-827 | AT&T | CHICGOZN01 | – | – | yes |
| 312-828 | AT&T | CHICGOZN01 | – | – | yes |
| 312-829 | AT&T | CHICGOZN01 | – | – | yes |
| 312-831 | AT&T | CHICGOZN01 | – | – | yes |
| 312-832 | AT&T | CHICGOZN01 | – | – | yes |
| 312-833 | Verizon | CHICGOZN01 | – | – | yes |
| 312-834 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-835 | Verizon | CHICGOZN01 | – | – | yes |
| 312-836 | AT&T | CHICGOZN01 | – | – | yes |
| 312-837 | Comcast | CHICGOZN01 | 2015-09-03 | yes | yes |
| 312-838 | T-Mobile | CHICGOZN01 | 2016-01-11 | yes | yes |
| 312-839 | American Messaging | CHICGOZN01 | 2001-04-13 | – | yes |
| 312-840 | AT&T | CHICGOZN01 | – | – | yes |
| 312-841 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-842 | AT&T | CHICGOZN01 | – | – | yes |
| 312-843 | AT&T | CHICGOZN01 | 2014-03-12 | yes | yes |
| 312-844 | AT&T | HINSDALE | – | yes | yes |
| 312-845 | AT&T | CHICGOZN01 | – | – | yes |
| 312-846 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-847 | Onvoy | CHICGOZN01 | 2019-06-28 | yes | yes |
| 312-848 | Verizon | CHICGOZN01 | – | – | yes |
| 312-849 | AT&T | CHICGOZN01 | – | – | yes |
| 312-850 | AT&T | CHICGOZN01 | – | – | yes |
| 312-851 | Spok | CHICGOZN01 | – | – | yes |
| 312-852 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-853 | AT&T | CHICGOZN01 | – | – | yes |
| 312-854 | RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | CHICGOZN01 | – | yes | yes |
| 312-855 | AT&T | CHICGOZN01 | – | – | yes |
| 312-856 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-857 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-858 | Lumen | CHICGOZN01 | 2015-12-21 | yes | yes |
| 312-859 | Verizon | CHICGOZN01 | – | – | yes |
| 312-860 | AT&T | CHICGOZN01 | – | – | yes |
| 312-861 | AT&T | CHICGOZN01 | – | – | yes |
| 312-862 | AT&T | CHICGOZN01 | 2006-01-25 | yes | yes |
| 312-863 | Windstream | CHICGOZN01 | 2001-04-10 | yes | yes |
| 312-864 | AT&T | CHICGOZN01 | – | – | yes |
| 312-865 | AT&T | WHEELING | – | yes | yes |
| 312-866 | T-Mobile | CHICGOZN01 | 2014-08-22 | yes | yes |
| 312-867 | AT&T | CHICGOZN01 | – | – | yes |
| 312-868 | Bandwidth | CHICGOZN01 | 2015-12-04 | yes | yes |
| 312-869 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-870 | FIRST COMMUNICATIONS, LLC | CHICGOZN01 | – | yes | yes |
| 312-871 | T-Mobile | CHICGOZN01 | 2015-08-28 | yes | yes |
| 312-872 | Lumen | CHICGOZN01 | 2018-07-12 | yes | yes |
| 312-873 | Verizon | CHICGOZN01 | – | – | yes |
| 312-874 | T-Mobile | CHICGOZN01 | 2015-05-22 | yes | yes |
| 312-875 | AT&T | CHICGOZN01 | – | – | yes |
| 312-876 | AT&T | CHICGOZN01 | – | – | yes |
| 312-877 | AT&T | CHICGOZN01 | 2014-08-12 | yes | yes |
| 312-878 | Peerless | CHICGOZN01 | 2008-02-04 | yes | yes |
| 312-879 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-880 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-881 | Windstream | CHICGOZN01 | 2001-04-10 | yes | yes |
| 312-882 | Verizon | CHICGOZN01 | – | – | yes |
| 312-883 | Bandwidth | CHICGOZN01 | 2014-11-12 | yes | yes |
| 312-884 | Windstream | CHICGOZN01 | 2001-04-10 | yes | yes |
| 312-885 | T-Mobile | CHICGOZN01 | 2015-09-22 | yes | yes |
| 312-886 | AT&T | CHICGOZN01 | – | – | yes |
| 312-887 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-888 | AT&T | CHICGOZN01 | 2012-01-13 | yes | yes |
| 312-889 | AT&T | CHICGOZN01 | 2015-06-25 | yes | yes |
| 312-890 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-891 | Spok | CHICGOZN01 | – | – | yes |
| 312-892 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-893 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-894 | Verizon | CHICGOZN01 | – | yes | yes |
| 312-895 | Lumen | CHICGOZN01 | – | – | yes |
| 312-896 | Lumen | CHICGOZN01 | – | – | yes |
| 312-897 | Verizon | CHICGOZN01 | 2015-03-23 | yes | yes |
| 312-898 | Verizon | CHICGOZN01 | – | – | yes |
| 312-899 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-900 | FRACTEL, LLC | CHICGOZN01 | 2019-01-18 | yes | yes |
| 312-901 | Spok | CHICGOZN01 | – | – | yes |
| 312-902 | AT&T | CHICGOZN01 | – | – | yes |
| 312-903 | American Messaging | CHICGOZN01 | 2001-04-13 | – | yes |
| 312-904 | AT&T | CHICGOZN01 | – | – | yes |
| 312-905 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-906 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-907 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-908 | AT&T | CHICGOZN01 | – | – | yes |
| 312-909 | Verizon | CHICGOZN01 | – | – | yes |
| 312-910 | Onvoy | CHICGOZN01 | 2022-09-19 | yes | yes |
| 312-912 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-913 | AT&T | CHICGOZN01 | – | – | yes |
| 312-914 | Verizon | CHICGOZN01 | – | – | yes |
| 312-915 | AT&T | CHICGOZN01 | – | – | yes |
| 312-917 | AT&T | CHICGOZN01 | – | – | yes |
| 312-918 | T-Mobile | CHICGOZN01 | 2013-08-19 | yes | yes |
| 312-919 | Verizon | CHICGOZN01 | – | – | yes |
| 312-920 | AT&T | CHICGOZN01 | – | – | yes |
| 312-921 | AT&T | CHICGOZN01 | 2008-07-21 | yes | yes |
| 312-922 | AT&T | CHICGOZN01 | – | – | yes |
| 312-923 | AT&T | CHICGOZN01 | – | – | yes |
| 312-924 | Windstream | CHICGOZN01 | – | – | yes |
| 312-925 | AT&T | CHICGOZN01 | – | – | yes |
| 312-926 | AT&T | CHICGOZN01 | – | – | yes |
| 312-927 | T-Mobile | CHICGOZN01 | 2002-08-21 | – | yes |
| 312-928 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-929 | T-Mobile | CHICGOZN01 | 2006-04-27 | yes | yes |
| 312-930 | AT&T | CHICGOZN01 | – | – | yes |
| 312-931 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-932 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-933 | T-Mobile | CHICGOZN01 | – | yes | yes |
| 312-934 | T-Mobile | CHICGOZN01 | 2014-12-08 | yes | yes |
| 312-935 | AT&T | CHICGOZN01 | – | – | yes |
| 312-936 | AT&T | CHICGOZN01 | – | – | yes |
| 312-937 | Verizon | CHICGOZN01 | 2014-09-25 | yes | yes |
| 312-938 | AT&T | CHICGOZN01 | – | – | yes |
| 312-939 | AT&T | CHICGOZN01 | – | – | yes |
| 312-940 | Peerless | CHICGOZN01 | 2013-09-20 | yes | yes |
| 312-941 | Spok | CHICGOZN01 | – | – | yes |
| 312-942 | AT&T | CHICGOZN01 | – | – | yes |
| 312-943 | AT&T | CHICGOZN01 | – | – | yes |
| 312-944 | AT&T | CHICGOZN01 | – | – | yes |
| 312-945 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-946 | AT&T | CHICGOZN01 | – | – | yes |
| 312-947 | AT&T | CHICGOZN01 | 2010-11-18 | yes | yes |
| 312-948 | Windstream | CHICGOZN01 | 2001-04-10 | yes | yes |
| 312-949 | AT&T | CHICGOZN01 | – | – | yes |
| 312-951 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-952 | AT&T | CHICGOZN01 | – | – | yes |
| 312-953 | AT&T | CHICGOZN01 | – | – | yes |
| 312-954 | AT&T | CHICGOZN01 | – | – | yes |
| 312-955 | RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | CHICGOZN01 | – | – | yes |
| 312-956 | AT&T | CHICGOZN01 | 2014-09-29 | yes | yes |
| 312-957 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-960 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-961 | AT&T | CHICGOZN01 | – | – | yes |
| 312-962 | Lumen | CHICGOZN01 | – | yes | yes |
| 312-963 | Spok | CHICGOZN01 | – | – | yes |
| 312-964 | Onvoy | CHICGOZN01 | – | yes | yes |
| 312-965 | Verizon | CHICGOZN01 | – | – | yes |
| 312-966 | T-Mobile | CHICGOZN01 | 2014-11-18 | yes | yes |
| 312-967 | Bandwidth | CHICGOZN01 | 2014-08-07 | yes | yes |
| 312-968 | Verizon | LA GRANGE | – | yes | yes |
| 312-969 | Verizon | LA GRANGE | – | yes | yes |
| 312-970 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-971 | Bandwidth | CHICGOZN01 | 2014-05-01 | yes | yes |
| 312-972 | AT&T | CHICGOZN01 | – | – | yes |
| 312-973 | Verizon | CHICGOZN01 | 2014-02-19 | yes | yes |
| 312-974 | AT&T | CHICGOZN01 | – | – | yes |
| 312-975 | T-Mobile | CHICGOZN01 | 2014-09-15 | yes | yes |
| 312-977 | AT&T | CHICGOZN01 | – | – | yes |
| 312-978 | T-Mobile | CHICGOZN01 | 2013-10-22 | yes | yes |
| 312-979 | AT&T | CHICGOZN01 | – | – | yes |
| 312-980 | AT&T | CHICGOZN01 | – | – | yes |
| 312-981 | Windstream | CHICGOZN01 | 2001-04-10 | yes | yes |
| 312-982 | Comcast | CHICGOZN01 | 2014-10-07 | yes | yes |
| 312-983 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-984 | AT&T | CHICGOZN01 | – | – | yes |
| 312-985 | Windstream | CHICGOZN01 | 2001-04-10 | yes | yes |
| 312-986 | AT&T | CHICGOZN01 | – | – | yes |
| 312-987 | AT&T | CHICGOZN01 | – | – | yes |
| 312-988 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-989 | AT&T | CHICGOZN01 | 2015-06-25 | yes | yes |
| 312-990 | AT&T | HINSDALE | – | yes | yes |
| 312-991 | AT&T | WHEELING | – | yes | yes |
| 312-992 | AT&T | CHICGOZN01 | – | – | yes |
| 312-993 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-994 | Windstream | CHICGOZN01 | 2001-04-10 | yes | yes |
| 312-995 | AT&T | CHICGOZN01 | 2014-08-12 | yes | yes |
| 312-996 | AT&T | CHICGOZN01 | – | – | yes |
| 312-997 | AT&T | CHICGOZN01 | – | yes | yes |
| 312-998 | Lumen | CHICGOZN01 | 2014-08-12 | yes | yes |
| 312-999 | Verizon | CHICGOZN01 | 2010-08-20 | yes | yes |
Frequently asked
How many prefixes does area code 312 have?
784 NXX blocks are assigned of 786 possible. Each block is 10,000 consecutive numbers, so the code currently covers about 7,840 thousand-number ranges across 8 rate centers.
What do the first three digits after 312 tell me?
They identify the block, which tells you the rate center it was allocated to and the carrier that received it. They do not tell you who serves the number today: portability moves numbers between carriers, and pooling splits a block between several of them.
Is a 312 prefix tied to a specific town?
To a rate center, which is billing geography rather than a town. NANPA abbreviates rate center names to ten characters and in large metros uses zone codes, so the name is a NANPA label, not a place name.
What does “pooled” mean in the 312 table?
That the block is in thousands-block pooling: carriers draw 1,000-number lots from it instead of taking all 10,000. 413 of 312's blocks are pooled, which is how regulators slowed down area code exhaustion – and why one prefix can belong to several carriers.
Source and limits
NANPA CO Code Assignment Records, all states, utilized codes, file updated 11/01/2026 – the rows where the record's Use field is “AS” (assigned). Unavailable codes are excluded. The records say who received a block and when, not who serves a particular number today.
More about this code: overview · carriers · spam complaints · local time