IL
United States geographic area code, in service since 1989-11-11. Part of the 464/708 overlay complex — ten-digit dialing required.
Split from 312. Created 847. Created 630. Created 464. Overlaid with 464 .
Prefix-level assignment does not equal number-level exhaustion; thousands-block pooling extends capacity. First assignment on record 2001-02-12, most recent 2026-08-27.
Area codes serve rate-center geographies, not municipal boundaries. “IL” identifies the jurisdiction, not an exact city footprint.
Top assignees
Ranked by assigned prefixes · initial assignee ≠ current carrier| Rank | Assignee | Prefixes | Share |
|---|---|---|---|
| 01 | ILLINOIS BELL TEL CO | 178 | 22.3% |
| 02 | T-MOBILE USA, INC. | 122 | 15.3% |
| 03 | NEW CINGULAR WIRELESS PCS, LLC - IL | 107 | 13.4% |
| 04 | LEVEL 3 COMMUNICATIONS, LLC - IL | 65 | 8.1% |
| 05 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL | 49 | 6.1% |
| 06 | PAETEC ITEL, LLC | 45 | 5.6% |
| 07 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 40 | 5% |
| 08 | TELEPORT COMMUNICATIONS AMERICA, LLC - IL | 34 | 4.3% |
| 09 | SPOK, INC. | 26 | 3.3% |
| 10 | ONVOY, LLC | 23 | 2.9% |
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- 2021-07-16 NPA 464 to Overlay NPA 708 (Illinois)
- 1989-11-11Area code 708 entered service (created from 312).
Planning letters & orders
Primary documents| Date | Document | Subject |
|---|---|---|
| 2021-07-16 | PL-562 ↗ | NPA 464 to Overlay NPA 708 (Illinois) |
| 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 |
| 1999-10-24 | PL-195 ↗ | NPA 872 to Overlay NPAs 312 and 773 (Illinois)NPA 464 to Overlay NPA 708NPA 331 to Overlay NPA 630 |
| 1989-04-21 | IL-89-04-028 ↗ | 312 NUMBERING PLAN AREA (NPA) CODE SPLIT IN ILLINOIS |