Area code 557 prefixes
84 of the 786 possible NXX blocks are assigned in area code 557 (10.7% of capacity), spread across 7 rate centers and 18 holders. The largest holders are NEW CINGULAR WIRELESS PCS, LLC - IL (23 blocks, 27.4%), ONVOY, LLC - MO (19 blocks, 22.6%), TELEPORT COMMUNICATIONS AMERICA, LLC - MO (15 blocks, 17.9%). Grouped by brand, AT&T accounts for 38 blocks; brand-attributable holders cover 88% 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 2022-08-08 to 2026-10-08, with 27 blocks handed out in 2023 alone. 83 blocks (99%) 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. 11 assigned blocks (254, 257, 258, 259, 261, 262…) are not yet in service: assigned to a carrier but not open for calls, so a caller ID from one is spoofed. 69 were growth assignments – additional blocks to a carrier that had already filled its earlier ones.
Largest holders in 557
| Holder of record, as NANPA names it | Brand | Blocks | Share |
|---|---|---|---|
| NEW CINGULAR WIRELESS PCS, LLC - IL | AT&T | 23 | 27.4% |
| ONVOY, LLC - MO | Onvoy | 19 | 22.6% |
| TELEPORT COMMUNICATIONS AMERICA, LLC - MO | AT&T | 15 | 17.9% |
| CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MO | Verizon | 8 | 9.5% |
| ONVOY SPECTRUM, LLC | Charter | 3 | 3.6% |
| T-MOBILE USA, INC. | T-Mobile | 2 | 2.4% |
| FIVE9, INC. | – | 2 | 2.4% |
| TERRA NOVA TELECOM INC. | – | 2 | 2.4% |
| COMCAST IP PHONE, LLC | Comcast | 1 | 1.2% |
| CALLWORKS CORPORATION | – | 1 | 1.2% |
| LEAP TELECOM, LLC | – | 1 | 1.2% |
| BOOST SUBSCRIBERCO L.L.C. | Dish | 1 | 1.2% |
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 84 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 |
|---|---|---|---|---|---|
| 557-200 | Onvoy | LADUE | 2022-08-08 | yes | yes |
| 557-201 | AT&T | KIRKWOOD | 2023-04-14 | yes | yes |
| 557-202 | Comcast | ST LOUIS | 2023-03-27 | yes | yes |
| 557-203 | T-Mobile | MEHLVILLE | 2023-05-19 | yes | yes |
| 557-204 | FIVE9, INC. | ST LOUIS | 2023-05-22 | yes | yes |
| 557-205 | AT&T | ST LOUIS | 2023-06-01 | yes | yes |
| 557-206 | AT&T | ST LOUIS | 2023-06-01 | yes | yes |
| 557-207 | FIVE9, INC. | OAKVILLE | 2023-06-15 | yes | yes |
| 557-208 | Onvoy | LADUE | 2023-09-07 | yes | yes |
| 557-209 | Onvoy | KIRKWOOD | 2024-02-29 | yes | yes |
| 557-210 | Verizon | LADUE | 2023-09-21 | yes | yes |
| 557-212 | T-Mobile | MEHLVILLE | 2023-09-29 | yes | yes |
| 557-213 | AT&T | ST LOUIS | 2023-09-29 | yes | yes |
| 557-214 | AT&T | ST LOUIS | 2023-11-13 | yes | yes |
| 557-215 | CALLWORKS CORPORATION | ST LOUIS | 2023-11-15 | yes | yes |
| 557-216 | AT&T | ST LOUIS | 2023-06-01 | yes | yes |
| 557-217 | AT&T | SAPPINGTON | 2023-11-15 | yes | yes |
| 557-218 | AT&T | LADUE | 2023-12-22 | yes | yes |
| 557-219 | Verizon | LADUE | 2024-01-18 | yes | yes |
| 557-220 | AT&T | CREVECOEUR | 2024-01-23 | yes | yes |
| 557-221 | Onvoy | MEHLVILLE | 2024-04-10 | yes | yes |
| 557-222 | LEAP TELECOM, LLC | ST LOUIS | 2023-05-04 | yes | yes |
| 557-223 | Verizon | LADUE | 2024-04-10 | yes | yes |
| 557-224 | AT&T | CREVECOEUR | 2023-12-15 | yes | yes |
| 557-225 | AT&T | LADUE | 2024-04-10 | yes | yes |
| 557-226 | Onvoy | CREVECOEUR | 2024-06-05 | yes | yes |
| 557-227 | AT&T | KIRKWOOD | 2024-07-31 | yes | yes |
| 557-228 | Verizon | ST LOUIS | 2024-11-25 | yes | yes |
| 557-229 | AT&T | KIRKWOOD | 2024-11-27 | yes | yes |
| 557-230 | AT&T | SAPPINGTON | 2024-12-30 | yes | yes |
| 557-231 | AT&T | ST LOUIS | 2025-01-03 | yes | yes |
| 557-232 | Verizon | LADUE | 2025-02-18 | yes | yes |
| 557-233 | Dish | ST LOUIS | 2025-02-25 | yes | yes |
| 557-234 | AT&T | ST LOUIS | 2025-03-13 | yes | yes |
| 557-235 | AT&T | KIRKWOOD | 2025-03-31 | yes | yes |
| 557-236 | Verizon | LADUE | 2025-04-24 | yes | yes |
| 557-237 | AT&T | LADUE | 2025-05-23 | yes | yes |
| 557-238 | AT&T | KIRKWOOD | 2025-06-20 | yes | yes |
| 557-239 | Verizon | ST LOUIS | 2025-07-02 | yes | yes |
| 557-240 | AT&T | LADUE | 2025-09-03 | yes | yes |
| 557-241 | Onvoy | LADUE | 2025-09-24 | yes | yes |
| 557-242 | Onvoy | ST LOUIS | 2025-09-24 | yes | yes |
| 557-243 | AT&T | ST LOUIS | 2025-10-09 | yes | yes |
| 557-244 | AT&T | KIRKWOOD | 2025-10-23 | yes | yes |
| 557-245 | AT&T | ST LOUIS | 2025-11-12 | yes | yes |
| 557-246 | WAVENATION, LLC | ST LOUIS | 2025-12-03 | yes | yes |
| 557-247 | AT&T | MEHLVILLE | 2025-12-11 | yes | yes |
| 557-248 | E. RITTER COMMUNICATIONS, LLC | ST LOUIS | 2025-12-29 | yes | yes |
| 557-249 | Onvoy | LADUE | 2026-01-13 | yes | yes |
| 557-250 | TPx | ST LOUIS | 2026-02-05 | yes | yes |
| 557-251 | AT&T | KIRKWOOD | 2026-02-26 | yes | yes |
| 557-252 | SHELCOMM | ST LOUIS | 2026-05-13 | – | yes |
| 557-253 | AT&T | KIRKWOOD | 2026-05-21 | yes | yes |
| 557-254 | AT&T | LADUE | 2026-05-27 | yes | no |
| 557-255 | Onvoy | LADUE | 2026-05-29 | yes | yes |
| 557-256 | Onvoy | MEHLVILLE | 2026-05-29 | yes | yes |
| 557-257 | Onvoy | CREVECOEUR | 2026-07-08 | yes | no |
| 557-258 | Onvoy | OAKVILLE | 2026-07-08 | yes | no |
| 557-259 | Onvoy | SAPPINGTON | 2026-07-08 | yes | no |
| 557-260 | Verizon | LADUE | 2026-07-23 | yes | yes |
| 557-261 | AT&T | KIRKWOOD | 2026-08-13 | yes | no |
| 557-262 | AT&T | ST LOUIS | 2026-08-20 | yes | no |
| 557-263 | AT&T | ST LOUIS | 2026-08-24 | yes | no |
| 557-264 | AT&T | LADUE | 2026-09-09 | yes | no |
| 557-265 | Onvoy | ST LOUIS | 2026-09-21 | yes | no |
| 557-273 | AT&T | ST LOUIS | 2023-01-25 | yes | yes |
| 557-333 | Onvoy | SAPPINGTON | 2025-07-15 | yes | yes |
| 557-362 | AT&T | ST LOUIS | 2023-01-25 | yes | yes |
| 557-444 | Onvoy | CREVECOEUR | 2025-07-15 | yes | yes |
| 557-454 | AT&T | ST LOUIS | 2023-01-25 | yes | yes |
| 557-467 | Onvoy | ST LOUIS | 2022-08-08 | yes | yes |
| 557-500 | Charter | ST LOUIS | 2022-08-12 | yes | yes |
| 557-507 | Charter | ST LOUIS | 2023-08-16 | yes | yes |
| 557-557 | Onvoy | ST LOUIS | 2023-05-15 | yes | yes |
| 557-567 | Charter | KIRKWOOD | 2024-11-07 | yes | yes |
| 557-653 | AT&T | ST LOUIS | 2023-01-25 | yes | yes |
| 557-666 | Onvoy | KIRKWOOD | 2026-10-08 | yes | no |
| 557-747 | AT&T | ST LOUIS | 2023-01-25 | yes | yes |
| 557-777 | TERRA NOVA TELECOM INC. | CREVECOEUR | 2022-08-24 | yes | yes |
| 557-880 | 8x8 | ST LOUIS | 2026-09-23 | yes | no |
| 557-888 | TERRA NOVA TELECOM INC. | KIRKWOOD | 2022-09-16 | yes | yes |
| 557-953 | AT&T | ST LOUIS | 2023-01-25 | yes | yes |
| 557-996 | AT&T | ST LOUIS | 2023-01-25 | yes | yes |
| 557-999 | WIRETAP TELECOM, LLC. | SAPPINGTON | 2022-09-16 | yes | yes |
Frequently asked
How many prefixes does area code 557 have?
84 NXX blocks are assigned of 786 possible. Each block is 10,000 consecutive numbers, so the code currently covers about 840 thousand-number ranges across 7 rate centers.
What do the first three digits after 557 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 557 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 557 table?
That the block is in thousands-block pooling: carriers draw 1,000-number lots from it instead of taking all 10,000. 83 of 557'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.
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