Telephone Numbers

State Map by Area Code

NANPA (North American Numbering Plan Administration)

What makes up a Telephone Number? Area Code + Prefix + Line Number

Area Code: A three digit number identifying the general geographic area in which a customer lives. Prefix: A three digit number that denotes the switch within a telephone exchange to which a call should be routed. Line Number: A four digit number that directs a call to an individual telephone line.

How many area codes does Missouri have? In the state of Missouri, there are nine area codes: 314, 557, 636, 816, 975, 660, 573, 235 and 417. Each area code has about 7.9 million numbers. There are 792 prefixes or blocks of 10,000 numbers in each area code available for public use. Some numbers in the blocks of 10,000 are reserved for testing codes and special uses (i.e., telephone numbers with prefixes such as 911, 711, 411, etc.)

Current Missouri Telephone Number Exhaust Dates

314/557: 4th quarter 2060

417: 2nd quarter 2032

573/235: 3rd quarter 2063

636: 3rd quarter 2075

660: 2nd quarter 2103

816/975: 3rd quarter 2069

The Missouri Public Service Commission continues to explore ways to improve how telephone numbers are distributed. Some of these number conservation efforts are described below.

Number Pooling: This means assigning companies numbers in blocks of 1,000 instead of blocks of 10,000. Pooling has been implemented in all six of Missouri’s area codes.

Reclamation: Under this practice, a company “returns” any unused numbers in its assigned block to the national pool of numbers. Once numbers are returned, they are available for use by another company.

Sequential Number Assignment: Telephone carriers are required to assign numbers within an already opened block of a thousand numbers, before opening another 1,000 number block.

Utilization Threshold: Telephone carriers are required to meet a utilization threshold (a certain percentage of a block of 1,000 numbers must be used before another block of 1,000 numbers is opened).

314 Area Code: The Missouri Commission worked with the North American Numbering Plan Administrator (NANPA) and the telecommunications industry on implementation of an overlay plan and the introduction of a new area code in the 314 area code region in Missouri. The new area code is 557. All existing 314 area code customers retained their current area code in the overlay area and their telephone numbers did not change. August 12, 2022 was the earliest date telephone numbers with a 557 area code were activated and used within the 314 area code. The 557 area code co-exists everywhere in this region with the 314 area code. All local calls within this region must be dialed using ten digits rather than seven digits.  Visit Case No. TO-2022-0010

816 Area Code: The Missouri Commission worked with the North American Numbering Plan Administrator (NANPA) and the telecommunications industry on implementation of an overlay plan and the introduction of a new area code in the 816 area code region in Missouri. The new area code is 975. All existing 816 area code customers retained their current area code in the overlay area and their telephone numbers did not change. October 13, 2023 was the earliest date telephone numbers with a 975 area code were activated and used within the 816 area code. The 975 area code co-exists everywhere in this region with the 816 area code. All local calls within this region must be dialed using ten digits rather than seven digits.  Visit Case No. TO-2022-0010

573 Area Code: The Missouri Commission worked with the North American Numbering Plan Administrator (NANPA) and the telecommunications industry on implementation of an overlay plan and the introduction of a new area code in the 573 area code region in Missouri. The new area code is 235. All existing 573 area code customers retained their current area code in the overlay area and their telephone numbers did not change. March 24, 2024 was the earliest date telephone numbers with a 235 area code were activated and used within the 573 area code. The 235 area code co-exists everywhere in this region with the 573 area code. All local calls within this region must be dialed using ten digits rather than seven digits.  Visit Case No. TO-2022-0250             

Elimination of 7-digit Local Dialing for 988 National Suicide Prevention Lifeline
On July 16, 2020, the FCC established 988 as the nationwide, easy-to-remember 3-digit dialing code for Americans in crisis to connect with suicide prevention and mental health crisis counselors. Visit Report and Order     

In order to accommodate the 988 code 7-digit local dialing was eliminated in the following Missouri area codes: 314, 417, 660 and 816. July 16, 2022 the "988" 3-digit dialing code was launched and routes calls to the National Suicide Prevention Lifeline. Visit Missouri Case No. TO-2021-0155