660
Area code
Statusin service
Introduced1997-10-12
JurisdictionMO, US
Local dialing10D
Time zoneCentral
Last verified2026-09-17
Utilization 67% of assignable prefixes assigned
As of 09/17/2026
0%531 of ~792 assignable NXX values (200–999 excl. N11)100%
Prefix-level assignment does not equal number-level exhaustion; thousands-block pooling extends capacity. First assignment on record 2001-01-18, most recent 2026-08-27.
Area codes serve rate-center geographies, not municipal boundaries. “MO” identifies the jurisdiction, not an exact city footprint.
Top assignees
Ranked by assigned prefixes · initial assignee ≠ current carrier| Rank | Assignee | Prefixes | Share |
|---|---|---|---|
| 01 | LEVEL 3 COMMUNICATIONS, LLC - MO | 63 | 11.9% |
| 02 | EMBARQ MISSOURI, INC. DBA CENTURYLINK - MO | 46 | 8.7% |
| 03 | ONVOY, LLC - MO | 41 | 7.7% |
| 04 | SOUTHWESTERN BELL | 40 | 7.5% |
| 05 | GRAND RIVER MUTUAL TEL CO | 36 | 6.8% |
| 06 | NEW CINGULAR WIRELESS PCS, LLC - IL | 34 | 6.4% |
| 07 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MO | 32 | 6% |
| 08 | AERIAL COMMUNICATIONS, INC. | 25 | 4.7% |
| 09 | WINDSTREAM MISSOURI, INC. | 23 | 4.3% |
| 10 | CHARITON VALLEY TEL. CO. | 18 | 3.4% |
Important: these are initial assignees from NANPA CO-code records — the carrier a prefix was originally assigned to. Because of number portability, the current serving carrier of any individual number may differ.
Change history
Recorded events for this NPA- 1997-10-12Area code 660 entered service (created from 816).
Planning letters & orders
Primary documents| Date | Document | Subject |
|---|---|---|
| 2021-01-08 | PL-556 ↗ | Transition to 10-digit dialing (for 988 as 3-digit access to National Suicide Prevention Lifeline) – supersedes PL-544 |
| 2020-08-17 | PL-544 ↗ | Transition to 10-digit dialing (for 988 as 3-digit access to National Suicide Prevention Hotline |
| 1997-07-28 | PL-077 ↗ | NANP-Split of 816 (Missouri) Numbering Plan Area (NPA) |