Area codes / Missouri / 557
The 557 area code
557 is an area code in Missouri, in the Central time zone. Get a local 557 number for your business, shared by everyone who answers it, or bring the 557 number you already have.
557 at a glance
Get a 557 business number
When you sign up for Onyx Phone, you pick a local number by area code: search 557, narrow it by the next three digits or the last four if you want something memorable, and it's yours on the spot. Which numbers are free changes daily. If you don't find one you like, 314 covers the same area.
The number rings everyone you assign to it, in the browser, on the iPhone and Android apps, and on desk phones, and texts from it are unlimited once US carriers approve your business. Your plan includes one number for each user, and more numbers are $5 a month.
Calling 557 customers
Local calls in 557 are dialed with all ten digits: the area code, then the number. Callers are on Central time, so set your business hours to match if most of your customers are here.
Calls from Onyx Phone show your business number, and once your business is verified, your caller ID name too, so 557 customers see who's calling.
Questions about area code 557
What state is area code 557?
Area code 557 is in Missouri.
What time zone is area code 557 in?
Area code 557 is in the Central time zone.
Is 557 an overlay area code?
Yes. 557 shares its area with 314. Numbers in either code ring the same region, and local calls there are dialed with all ten digits.
Can I get a 557 business number?
Onyx Phone sells US local numbers. When you pick your number, search the 557 area code; which numbers are free changes daily. If none are free, 314 covers the same area.
Can I keep the 557 number I already have?
Yes. Moving a number to Onyx Phone is free on every plan and usually takes 3 to 7 business days. You answer on a temporary number until it moves.
Included on every plan
Starter is $17, Business is $29, Scale is $42 per user a month, or less billed yearly. The plan includes a business number for each user and unlimited calling and texting in the US and Canada. Every plan starts with a 7-day free trial, and moving your current number over is free.
Area code data from the North American Numbering Plan Administrator (NANPA), file of October 24, 2026.