Is the north country really running out of 315 area-code space?

State and regulatory officials think so. They have said previously that the 315 region will exhaust its supply of available phone numbers in 2010.

Earlier this year, the state's Public Service Commission suggested four options to deal with the problem and asked for public response.

But on March 14, the Public Utility Law Project of New York submitted a petition asking the state to stop considering the four relief options and instead investigate whether the second area code actually is needed.

On Monday, PSC suspended the public comment period on the four plans until the issue can be resolved.

James A. Denn, a spokesman for the commission, said the suspension will allow the petition to be reviewed. The proceedings on the 315 area-code change continue, he said.

The state estimates that 2.7 million of the 8 million assignable seven-digit phone numbers in the 315 area code are in use. Even though many numbers remain, a total of 83 percent of the available phone numbers have been assigned, rendering them unavailable.

The North American Numbering Plan Administration, which oversees numbering for telephones in Canada, the Caribbean and the United States, assigned telecommunications carriers blocks of 10,000 assignable numbers.

A decade ago, as available numbers in the north country were running low, NANPA reduced the numbers that telecommunications carriers could assign to blocks of 1,000, a tenth of the number in each exchange.

The change meant that the 315 area code, originally predicted to exhausted by 2002, received enough new numbers to last until 2010.

In an audit of the NANPA numbering distribution, the Public Utility Law Project of New York found that small, rural towns were receiving what it believed were a disproportionate share of available numbers, which are distributed by the three-digit exchange that follows an area code.

In Alexandria Bay, for example, five competing carriers assigned five exchanges and 50,000 numbers to the population of 4,097. Harrisville, with a population of 653, had four exchanges from four different carriers and 40,000 available numbers.

The exchanges ate up available phone numbers, creating an artificial shortage, said Gerald A. Norlander, executive director of PULP.

"It looks like a lot of three-digit local exchange numbers were obtained for areas that would seem not to require them," he said. "It would seem that the rules are not being followed. Or something's going on that no one understands."

The problem, said Mr. Norlander, is the way telephone numbers are assigned by their exchanges, which include blocks of about 10,000 potential telephone numbers.

By reclaiming unused seven-digit numbers, he said, the life of the 315 area code could be extended beyond 2010.

"It takes a lot of money, time and expense to change everybody's numbers," said Mr. Norlander. "If you don't have to do it, don't do it."

Earlier this year, the Public Service Commission offered four suggestions to deal with the exhaustion of the 315 area code. Three of these would divide the north country geographically, which would give Jefferson, Lewis and St. Lawrence counties a new area code.

The fourth option would create an overlay district in which existing numbers would remain unchanged, but any new numbers would have a new area code.

In a recent survey by the Greater Watertown-North Country Chamber of Commerce, local businesses showed a preference for the overlay option. By leaving businesses' phone and fax numbers unchanged, such an option would save money on reprinting items such as advertising, stationary and business cards.

Mr. Norlander said he does not believe a new area code is necessary. His agency, having analyzed existing numbers, believes there is an abundance of seven-digit phone numbers languishing unused, he said.

Under current regulations, 75 percent of an area's exchange must be filled before another can be used. Mr. Norlander said exchanges don't appear to be filling up before a new one is assigned to an area.

NANPA spokesman Marc Abshire said he had not seen the PULP motion, but said that analysis on number availability is taken very seriously.

"We stand behind our projection," he said. "NANPA constantly re-evaluates our projections and issues a report twice a year as a result of that. We're actively keeping our eye on the exhaust rates."

The PULP petition asking for an investigation of the 315 area-code region will be reviewed by an administrative law judge at the state Department of Public Service.

Mr. Norlander said his group will be happy with a more thorough explanation about the current use of numbers, even if such an investigation proves that another area code is needed.

"If the numbers are really committed and used in some honest way, that's the end of the story," he said. "It's not the end of the world."