BISMARCK, N.D. (AP) -- North Dakota is getting closer to running out of phone numbers, a consequence of the proliferation of cell phones, data lines, new companies -- and number waste.

State regulators are planning for the day when North Dakota must add a second area code, said Tony Clark, president of the state Public Service Commission. North Dakota, which has the 701 area code, is one of 11 states, including Wyoming, with only one code.

Phone customers in a geographic region of North Dakota will be assigned a new, three-digit area code, or the state will get a code "overlay" -- meaning that newly assigned phone numbers, no matter where they're needed, will be given a different area code.

NeuStar Inc., a Sterling, Va., company that oversees the nation's phone numbering system, believes North Dakota will exhaust its phone-number supply in the spring of 2012. Company officials briefed the PSC last week.

Two of North Dakota's neighboring states, South Dakota and Montana, are among the 11 that have only one area code. NeuStar predicts Montana will run out of phone numbers in 2010, while South Dakota will deplete its supply in 2012.

Other states with only one area code are Delaware, Idaho, Maine, New Hampshire, New Mexico, Rhode Island, Vermont and Wyoming. Wyoming is likely to keep its one-area-code status the longest; NeuStar forecasts that it won't exhaust its phone-number supply until 2022.

Normally, state regulators begin preparing for a new area code at least three years in advance, Clark said. At the commission's request, the Legislature this year gave the agency more authority to manage phone numbers and delay the need for another area code.

Some of North Dakota's telephone companies are already taking steps to husband the dwindling supply of numbers, which usually are granted in blocks of 10,000 each.

One method is to split a block of numbers into chunks of 1,000 and share them with other providers, which can lessen the need for companies to request a new block of 10,000 digits.

Only about 1 percent of the state's assigned phone number blocks were pooled at the end of last year, a Federal Communications Commission report says.

NeuStar's prediction also assumes North Dakota is using up numbers more quickly than what is actually happening, said Mike Whaley, a staff advocate for Qwest who is an expert on telephone numbering.

The company assumes North Dakota telecommunications providers are getting at least two new blocks of numbers each month, Whaley said. Only four have been assigned so far this year, all of which were taken in February by Nextel, the wireless phone company. It recently merged with Sprint.

"I think it's premature to say that (telephone number) exhaust is imminent in North Dakota," Whaley said. "The date that's posted out there has more life in it than what they're registering."

On the Net:

NeuStar Inc.: http://www.neustar.biz/index.cfm

North American Numbering Plan Administration: http://www.nanpa.com/about--us/index.html

Federal Communications Commission Q&A on area codes:

http://www.fcc.gov/Bureaus/Common--Carrier/Factsheets/areacode.html