With "507" running out of numbers, a new area code is planned for southern Minnesota.

But relax, denizens of the 507: You'll likely keep your code. The new number will be for new phone customers.

During the first quarter of 2025, the 507 area code — which covers all of southern Minnesota from Rochester to Marshall — is expected to exhaust its available numbers, according to a regulatory filing Tuesday by the North American Numbering Plan Administrator.

The telecommunications industry is recommending the "overlay" of a new area code in 507, since that's the most "customer-friendly" method, said the filing with the Minnesota Public Utilities Commission, which must sign off on any area code change. The new number has not been chosen.

With an overlay, phone customers within 507 would retain their code, though they would have to dial 10 digits instead of seven within the traditional 507 area.

The 507 code's territory won't change. New customers within it will be assigned a new area code in a transition slated for 2025.

An alternative to overlaying a new area code is to split 507's turf into east and west regions, one of which would get a new code, the filing said.

Luverne, Worthington, Jackson, Mankato, New Ulm and Gaylord would be in one code; Austin, Albert Lea, Owatonna, Rochester, Winona and Waseca in another.

However, a new area code hasn't been introduced via a geographic split since 2007, the PUC filing said. A split is more daunting these days due to changing technologies.

The 507 area code was created in 1954 — the first to join the state's original area codes of 612 and 218.

With the proliferation of fax machines, pagers and now-ubiquitous cellphones, a slew of new area codes came about in Minnesota at the turn of the last century.

The western part of the 612 code became 320 in 1996, encompassing such cities as St. Cloud, Alexandria and Willmar. The 651 code now covering St. Paul and a swath of eastern Minnesota was carved out of 612 in 1998.

Two years later, 612 was subdivided again with the creation of the 952 and 763 area codes for the southwest and northwest suburbs and exurbs, respectively. There was much to-do over who got the new codes — Minneapolis or the suburbs.

The 218 area code — that of Duluth, the Iron Range and the Brainerd lakes region — is expected to be exhausted and in need of new area code in 2029, according to projections by the North American Numbering Plan Administrator.

Covering less densely-populated northern Minnesota, 218 is the state's largest area code by land mass.