605
Area code
SD
United States geographic area code, in service since 1947-01-01.
Statusin service
Introduced1947-01-01
JurisdictionSD, US
Local dialing10D
Time zoneCentral / Mountain
Last verified2026-09-17
Utilization 95.8% of assignable prefixes assigned
As of 09/17/2026
0%759 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 2001-01-16, most recent 2026-08-04.
Area codes serve rate-center geographies, not municipal boundaries. “SD” identifies the jurisdiction, not an exact city footprint.
Top assignees
Ranked by assigned prefixes · initial assignee ≠ current carrier| Rank | Assignee | Prefixes | Share |
|---|---|---|---|
| 01 | QWEST CORPORATION | 104 | 13.7% |
| 02 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - SD | 100 | 13.2% |
| 03 | NEW CINGULAR WIRELESS PCS, LLC - IL | 81 | 10.7% |
| 04 | MIDCONTINENT COMMUNICATIONS. - SD | 34 | 4.5% |
| 05 | CLARITY TELECOM, LLC DBA BLUEPEAK | 33 | 4.3% |
| 06 | VENTURE COMMUNICATIONS COOPERATIVE | 30 | 4% |
| 07 | INTERSTATE TELECOM COOP, INC. - SD | 27 | 3.6% |
| 08 | GOLDEN WEST TEL COOP INC DBA GOLDEN WEST TELECOMM | 27 | 3.6% |
| 09 | VIVIAN TEL CO DBA GOLDEN WEST TELECOMMUNICATIONS | 19 | 2.5% |
| 10 | ONVOY, LLC - SD | 19 | 2.5% |
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- 1947-01-01Area code 605 entered service.
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 |