Get a local business phone number in St. Clair, MO

What area code is St. Clair, MO?

St. Clair city is a Census place in Franklin County, Missouri, with an estimated 4,748 residents in 2024. All 6 exchanges NANPA lists for its rate center are in area code 636. St. Clair is in the Central time zone.

According to NANPA's dialing-plan data, local calls within 636 are dialed as seven digits and toll calls as 1 plus ten digits.

Phone carriers in St. Clair

5 carriers hold the 6 exchanges assigned to St. Clair's rate center. Southwestern Bell has the most, with 2. 5 of them are pooled codes, which the holder shares with other carriers in blocks of 1,000 numbers. Holding a code means NANPA assigned that block of numbers to the carrier for this rate center; individual numbers may since have been ported elsewhere.

Local prefixes for St. Clair

A prefix (NXX) is the three digits after the area code. Numbers starting with these prefixes are rated as local to St. Clair. The earliest assignment date recorded in the file for these codes is 2003. 1 of the 6 were assigned in 2020 or later.

When St. Clair's exchanges were assigned

The table groups St. Clair's exchanges by the decade NANPA recorded them as assigned.

Rate centers and local calling in St. Clair

NANPA ties every exchange to a rate center. For St. Clair that is ST CLAIR, so a number from one of these exchanges reads as local to people in and around St. Clair.

New local numbers are drawn from carrier inventory, so the exact 636 numbers available change over time; porting an existing number is free.

Businesses around St. Clair

St. Clair is part of the St. Louis, MO-IL metro area, home to 2.8 million people in 2024. County Business Patterns counted 69,470 business establishments in the St. Louis, MO-IL metro area in 2023, employing 1,263,674 people. The largest sectors by establishment count are health care and social assistance (10,427), retail trade (8,095), and professional, scientific, and technical services (7,057).

Setting up a St. Clair business line

Callata Office costs $99 per month for up to 5 people, and each additional user is $20 a month. That covers up to 3 local numbers, calling from a browser or your cell, transcribed voicemail, recorded calls with AI summaries, after-hours routing and E911 on each number.

Porting a number you already use in St. Clair is free, and business texting is available once the carrier registration (10DLC) is approved; the registration carries a one-time $49 fee. Which specific numbers are open in a given area code depends on carrier inventory at the time you sign up.

AI agents are optional: an AI receptionist or scheduler can pick up when the team is busy or closed, take a message, send a text or email, or transfer the call. They draw on prepaid AI minutes ($0.25/minute), disclose that they are AI, and outbound AI calls require prior consent and are limited to 8am–9pm.

Per-seat phone plans multiply by headcount. For the rounded average establishment size in the St. Louis, MO-IL metro area, 18 users on RingCentral RingEX Core come to $540.00 a month and on Ooma Office Pro $449.10, at month-to-month list prices checked September 28, 2026. Callata comes to $359.00 a month for 18 users ($99 a month with 5 users included, then $20 per additional user), below both.