NumberResearchRecent prefix assignments
0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/20/2026
The Code holder is who opened each NPA-NXX prefix — not necessarily who holds the numbers. A prefix is 10,000 numbers, but under pooling its ten 1,000-number blocks are handed out individually, often to different carriers; the code holder may hold only one block, or none. The Thousands-blocks column shows how the ten blocks are really split — click which blocks → to see who holds each 1,000-number block and its last-4-digit range. Assignments are initial assignments; the current serving carrier may differ due to portability.
| Assigned | NPA-NXX | Thousands-blocks taken (last-4 opening) | Code holder | OCN | Rate center | State |
|---|---|---|---|---|---|---|
| 2018-03-16 | 510-607 | 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 7 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD MN-PD | CA |
| 2001-04-23 | 510-746 | 6XXX8XXX · 2 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD TRNID | CA |
| 2001-03-01 | 510-933 | not yet reported which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | FRNK OLIVR | CA |
| — | 510-239 | 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD ALMD | CA |
| — | 510-300 | 4XXX5XXX7XXX · 2 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | HAYWARD | CA |
| — | 510-342 | 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 6 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | HAYWARD | CA |
| — | 510-343 | 1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD TRNID | CA |
| — | 510-401 | 0XXX1XXX3XXX4XXX5XXX7XXX9XXX · 5 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | FRNK GRNLF | CA |
| — | 510-403 | 0XXX1XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | FRNK OLIVR | CA |
| — | 510-456 | 0XXX5XXX6XXX8XXX · 2 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | FRNK MAIN | CA |
| — | 510-463 | 1XXX3XXX4XXX7XXX8XXX9XXX · 4 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD MN-PD | CA |
| — | 510-496 | 1XXX3XXX4XXX9XXX · 3 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD MN-PD | CA |
| — | 510-585 | 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | FRNK MAIN | CA |
| — | 510-698 | 1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 5 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD FRTVL | CA |
| — | 510-809 | 5XXX6XXX7XXX which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD BKLY | CA |
| — | 510-859 | 3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD BKLY | CA |
| — | 510-940 | 3XXX5XXX6XXX8XXX9XXX · 4 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | HAYWARD | CA |
| — | 510-995 | 0XXX6XXX7XXX8XXX · 3 holders which blocks → | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD ALMD | CA |
Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/20/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.