Beginning in 2024, all local calls within Missouri’s 573 area code will have to be placed using the full 10 digits of your phone number.

A new overlay 235 area code is being created because there weren’t that many available phone numbers left, according to Scott Rupp with the Missouri Public Service Commission.

“This has happened in multiple different parts of the state,” said Rupp. “It’s constantly happened around the country. So many digits, you can only change those in order so much. It’s not an infinite number of phone numbers. We were projecting that beginning in 2025, you would be out of phone numbers.”

Existing customers with a 573 area code will not lose or have to change their phone number. The new area code will be given to customers in the 573 region who request new service or additional phone lines.

A six-month permissive dialing period began at the end of August to give customers time to adjust to the dialing changes. On February 24, 2024, all local calls made within the 573 area code must be placed using 10 digits, that’s your area code and the 7-digit telephone number.

“It’s just new numbers coming on will be a 235 area code that serves the same area as the 573,” Rupp said. “That’s why you have to dial the 10 numbers, because not everybody in your geographic area may have that 573 area code. Some new people might have 235.”

Rupp said residents be advised to update your safety and security equipment now.

“This is something that comes up to us. Let’s say you have a new hospital that comes in and they need a whole bunch of phone numbers, but we’re running out of phone numbers,” he said. “You have to get approval for those to be able to go through. So they kind of have to get approval so that they know that if they’re coming in, hey, if you’re putting in a new system, we think that there’s a new overlay coming, you should prepare for that or be able to reprogram very quickly.”

Medical alert devices and alarm and security systems must be programmed to use the full 10-digit dialing. Using three digits to reach 911 or 988 services will remain unaffected.

The 573 area code covers most of the eastern half of Missouri outside of the immediate St. Louis area.

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