Ashburn area residents are hailing a change in telephone calling boundaries as a great way for them to save money as well as a unifying force in their growing community.

A recent action by U.S. District Judge Harold H. Greene cleared the way for most residents and businesses in the Ashburn and Leesburg areas to pay greatly reduced charges for making phone calls to areas east of Broad Run.

The change, expected to take effect about mid-1991, follows more than a year of citizen activism that helped bring together the Ashburn Village and Ashburn Farm communities in a drive to alter phone billing policies resulting from the landmark 1984 divestiture decision by Greene.

"It's a real oportunity to bring these communities together," said state Sen. Charles L. Waddell (D-Loudoun), who worked with state and local officials, residents and others to seek the money-saving change.

"A lot of people got together" over the issue, commented Jackie Silvay, who edits a newsletter in Ashburn. "It's probably the only issue right now" on which virtually all residents of the community agree, she said.

Added Lori LaSpada, who was active in the campaign, "It was a wonderful Christmas present."

One of the results of the 1984 divestiture decision was that phone service areas were carved out of the countryside. Most of Northern Virginia was placed in a self-contained area; that area includes Countryside, Sterling Park, Fairfax County and other areas generally east of Broad Run and Route 28.

Ashburn, which then was just a tiny village, and the rest of central and western Loudoun were placed in the Culpeper calling area. Full long-distance rates generally were applied to calls between the two areas, even if the distance was a mile or two.

But Ashburn's growth -- now more than 2,000 residents, by most estimates -- and its continued identification with people and places in the Northern Virginia calling area meant that a lot of people started paying a lot of money for phone calls that they thought were, or should have been, local calls.

"People moving into there had been blindsided" by the phone bills, Waddell said. "The first phone bill we had was over $300," said LaSpada, who runs a business out of her home. "It was a real shock."

She and a few others in the Ashburn area got together, contacted officials and lobbied for a change. Some wanted to be included in the Northern Virginia calling area, but most realized that it would be easier to seek an Extended Area Calling plan that would increase their basic monthly phone bills slightly but reduce their toll charges to Northern Virginia numbers. About 90 percent of affected customers responded positively to a poll regarding the plan.

With the support of local officials, Virginia's State Corporation Commission and, recently, Greene, that revision has been approved. It will be mandatory for all phone customers whose numbers begin with 729, 777 and 771, said Jim Ellington, Chesapeake & Potomac Telephone Co. manager for the Leesburg, Warrenton and Winchester areas.

The phone company took a neutral stance in the issue, Ellington noted, adding that steps are being taken to implement the change. "A significant amount of work needs to be done," including equipment changes, he said. "We're working toward a June 1 date."

Basic rates will rise by different amounts depending on the type of service. Ellington said residents with so-called flat rate service will see the local charge increase from $12.60 to $13.59. But additional charges for their calls to most of Sterling, Fairfax County, Falls Church, Arlington and Alexandria will drop about 80 percent per call.

If a residential customer makes at least three calls to those areas in a month, the caller is likely to save money overall, Ellington said. Calls from the Ashburn, Leesburg and Lucketts areas to those other Northern Virginia locations will be measured and charged by time but not by distance, he said. He emphasized that they will still be toll calls, not free calls.

The basic service cost to business accounts will rise nearly $4 a month, Ellington said.