The 573 area code serves most of eastern Missouri outside metro St. Louis — Columbia, Jefferson City, Cape Girardeau, Rolla, Hannibal, Poplar Bluff, Sikeston, Farmington and Fort Leonard Wood — in service since January 7, 1996, when it split from St. Louis’s 314, and sharing its entire territory with the 235 overlay since March 24, 2024.
That 573 you can’t place is more likely a Jefferson City state office, a Columbia campus desk, or a Fort Leonard Wood line than anything nearby — and the three digits confirm none of it.
573 quick facts
| Question | Short answer |
|---|---|
| Debut | January 7, 1996 |
| Created from | Split of St. Louis’s 314 |
| Overlay on file | 235, in service March 24, 2024 |
| Principal cities | Columbia, Jefferson City, Cape Girardeau, Rolla, Hannibal |
| Local dialing | Ten digits, mandatory since February 24, 2024 |
| Time left | 3Q 2063 for the shared 235/573 pool (NANPA, April 2026) |
Where is area code 573, exactly?
NANPA’s planning letter for the territory draws the map in one clause — the code “covers most of the eastern half of Missouri and includes the state capital of Jefferson City.” Its community roster runs Columbia, Jefferson City, Cape Girardeau, Rolla, Hannibal, Poplar Bluff, Sikeston, Farmington and Fort Leonard Wood, plus many smaller towns: the college city, the capitol dome, the Army post and the Mississippi River ports all share one code.
The edges are other Missouri codes on every landward side. Metro St. Louis runs on 314 and its 557 overlay, with 636 wrapped around the outer suburbs; north-central Missouri dials 660, the Kansas City side uses 816 and 975, and the Ozark southwest belongs to 417. Across the Mississippi, the Illinois bank splits: 217 faces Hannibal and the northern river towns, while 618 and its 730 overlay hold the shore opposite Ste. Genevieve and Cape Girardeau.
Half of 314 becomes its own code
Missouri entered the numbering plan on January 1, 1947 holding two codes: 314 for St. Louis and the eastern outstate, 816 for Kansas City’s half. For forty-nine years, a call from Columbia, the capital or the river counties went out wearing St. Louis’s digits.
The departure is dated precisely in NANPA’s NPA database: 573 assigned August 31, 1995, in service January 7, 1996, parent code 314. The paperwork predates NANPA itself — the modern planning letter for the territory cites one Bellcore-era predecessor, information letter IL 95/08-015. What moved was everything outside greater St. Louis: the university corridor, the seat of state government, and the river country down toward the bootheel.
That split opened a statewide redrawing that never came back east: 660 left 816 in October 1997, 636 left the St. Louis metro in May 1999, and the 1996 boundary around 573 has not shifted since.
235: relief on a deadline
By 2022 the prefix ledger was thin. On May 1, 2022, the Missouri Public Service Commission approved an all-services distributed overlay in File No. TO-2022-0250; NANPA assigned 235 the following day, and Planning Letter PL-596 of June 17, 2022 published the schedule that carried it out.
The timeline ran: customer education from February 24, 2023; permissive ten-digit dialing from 12:01 a.m. Central on August 26, 2023; mandatory ten-digit dialing on February 24, 2024; the overlay in service on March 24, 2024. Carriers could order 235 prefixes through NANPA from January 18, 2024, and ran routing checks against a test number — 235-235-1235 — that answered with a recording from December 24, 2023 until April 24, 2024.
One rule in PL-596 keeps the new code scarce: a 235 prefix may be assigned only after nothing assignable remains on the 573 shelf, so mid-Missouri numbers still arrive wearing the 1996 digits. How that NPA-NXX prefix inventory drains and refills is its own subject.
How close it ran is preserved in NANPA’s own exhaust table: the late-2023 study projected this territory exhausting in the first quarter of 2024. The overlay entered service on March 24 — inside the very quarter the forecast named — and the next study moved the horizon out four decades.
Ten digits, on the overlay’s calendar
When the 988 crisis line pushed 82 area codes to ten-digit dialing in 2021, Missouri placed four on NANPA’s PL-556 list — 314, 417, 660 and 816 — and 573 was not among them. Mid-Missouri kept dialing seven digits through the national conversion and for two years after it.
The overlay ended the holdout on its own schedule: permissive from August 26, 2023, mandatory from February 24, 2024. NANPA’s current entry reads ten digits on local calls, 1 plus ten on toll, and 0 plus ten for operator-assisted calls, with 1-plus-ten local dialing accepted at each provider’s discretion. Within Missouri, only 636 still connects a seven-digit local call.
From weeks left to 2063
The 2026-1 exhaust study, dated April 2026 and computed on numbering data as of March 1, stretches the combined 235/573 pool into the third quarter of 2063 — seven quarters beyond the October 2025 study’s call of late 2061, a move the report pins on reduced demand, both past and projected.
Nothing since has disturbed it. The lone mid-year correction — July 6, 2026 — re-dated four Texas forecasts, and as of mid-August 2026 NANPA’s database carries 573 with no jeopardy note and no relief file opened. The state’s pressure sits elsewhere — southwest Missouri’s 417 holds the nearest date on the board at mid-2032 — while the territory that actually hit the wall in 2024 now owns one of the calmer forecasts in the state. And if the sequence ever repeats, our explainer on area codes maps the ending in advance: an overlay changes no existing number by a single digit.
Working half a state from one caller ID
For outbound teams, the code’s size is the asset. One set of digits reads local from the capital press corps to the flagship campus to every county seat along the river, so the answer-rate case for matching your display to the market applies from Hannibal to Sikeston without switching numbers.
What the display cannot do is authenticate anyone. Spoofing pastes a 573 caller ID onto traffic from anywhere on earth, so looking local and being verifiable stay separate questions — settled at the carrier layer, where a STIR/SHAKEN signature either stands behind the call or doesn’t.
SIPNEX works that layer under its own FCC license — a direct carrier, not a reseller. Local DID numbers are stocked per rate center, mid-Missouri exchanges included while inventory lasts, and land on your existing PBX or dialer over SIP trunking. Each outbound call goes out signed A-level under the STIR/SHAKEN certificate SIPNEX holds in its own name, with RespOrg-managed toll-free alongside when a campaign needs both.
The questions 573 keeps raising
Which Missouri communities does the 573 area code serve?
Most of eastern Missouri outside metro St. Louis. NANPA’s planning letter names Columbia, Jefferson City, Cape Girardeau, Rolla, Hannibal, Poplar Bluff, Sikeston, Farmington and Fort Leonard Wood, plus many smaller towns, and the same footprint has carried the 235 overlay since March 2024. Metro St. Louis (314, 557, 636), north-central 660, the Kansas City side (816, 975) and the southwest’s 417 hold the rest of the state.
When did the 573 area code break away from 314?
January 7, 1996. NANPA’s database logs the code assigned August 31, 1995 and in service that winter as a split of St. Louis’s 314, one of Missouri’s two 1947 originals. The split left 314 holding greater St. Louis and handed everything outstate to the new code — and no boundary change has touched 573 since.
Are 235 and 573 area code numbers interchangeable?
Practically, yes — both codes cover identical territory and dial identically. The difference is scarcity: under PL-596, NANPA assigns a 235 prefix only after the last assignable 573 prefix is spoken for, so 573 numbers remain the overwhelming majority on mid-Missouri caller ID. A business ordering local DIDs in the region today will still generally receive 573 stock.
Why did the 573 area code skip the 2021 ten-digit change?
Because it wasn’t on the list. NANPA’s PL-556 (January 8, 2021) converted 82 codes for the 988 crisis line, and Missouri’s entries were 314, 417, 660 and 816 — not 573. Mid-Missouri dialed seven digits until the 235 overlay imposed its own calendar: permissive ten-digit dialing from August 26, 2023, mandatory from February 24, 2024, a month before 235 entered service.
Is the 573 area code anywhere near running out of numbers?
Not close — the current projection reads third quarter of 2063. NANPA’s April 2026 study moved the shared 235/573 pool seven quarters later on reduced demand, the July 6, 2026 corrections touched only Texas, and the database shows neither jeopardy nor relief planning. The territory that nearly exhausted in early 2024 now holds one of Missouri’s longer runways.
Thirty years after outstate Missouri got its own dial, the digits still mean Columbia, the capital and the river country. SIPNEX issues 573 numbers under a direct FCC carrier license, delivers them anywhere over SIP trunking, and signs each call at A-level attestation with its own certificate. Review DID and trunk pricing, reach the carrier team, or call (833) 665-2220.
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