OKLAHOMA CITY - The Oklahoma City area code, 405, is exhausted. Officials said the metro has run out of phone numbers and a new code is needed.

According to the North American Numbering Planning Administration, it takes roughly 800,000 phone numbers to exhaust an area code. While the change isn’t expected to happen for about a year, work is already underway to make sure the change happens smoothly.

Current 405ers won’t have to get a new number, instead, the metro will get an overlay code because splitting area codes is complicated and largely unpopular. The overlay would operate in the same area as 405 without splitting the metro.

“An area code split, it does require number changes and most consumers do not want that,” Beth Sprague Director of NANPA said.

Adding an overlay can be a technical process. According to Sprague seven-digit dialing would be eliminated in the metro, meaning every number would have to include the area code. That means work for telecom providers, government agencies and companies to update phone systems to accommodate the new numbers. In bill letters and notifications also need to be sent to customers and users. It’s why Sprague said work must be done now before 405 is fully exhausted.

“As long as all your devices can handle the ten-digits, like alarm companies, but they're all notified it should not be any surprise to anyone,” Sprague said.

This new area code will be Oklahoma's fifth area code. The first was 405 way back in 1947. Just a few years after that Tulsa got its own area code 918 in 1953. Then, more than 40 years later, as the population in the cities grew the rest of the state split off to become 580 in 1997. Finally, in 2011, 918 got Oklahoma's first overlay code 539.

The code that will overlay here in the metro has already been chosen but Sprague said she can't say what it is; the information is proprietary. The order to allow the overlay also has to be made by the Oklahoma Corporation Commission, officials expect that to happen sometime early 2020.