(This story has been updated to correct the total of the state investment.)

State officials vowed 18 months ago to be more creative in closing the digital divide in Western Massachusetts.

One of the most unusual approaches yet is now on the table.

To bring high-speed internet to the towns of New Marlborough, Sandisfield and Tolland, directors of the quasi-public Massachusetts Broadband Institute have agreed in theory to pay $4.77 million to a private company, Frontier Communications.

That is the sum of the three communities' full last-mile allocations plus an additional $1 million requested by Frontier.

Those towns would together pay Frontier an additional $15.5 million over 15 years to design, build, own and operate a fiber-to-the-home network that would reach 96 percent of premises.

By agreeing to support the plan, the state is kicking in $1 million more than it had planned to make available to the communities, which are among the smallest of the unserved communities on MBI's map. The towns were already eligible for $3.77 million in state grants.

"We felt this is an interesting model," said Peter Larkin, the MBI board chairman and special adviser to the state Executive Office of Housing and Economic Development. "We felt we could be supportive."

The move comes as the state works to bring "last-mile" broadband connections to rural communities.

Edmund Donnelly, the MBI's deputy director, acknowledged that the Frontier deal is complex.

"There are a few more moving parts in this than in our other cable proposals," he said.

As of September, projects were underway — or plans in place — to bring service to 37 of an initial list of 45 towns. That tally includes the three communities that would be served by Frontier.

Before the new plan can move forward, the state must give other private companies an equal crack at the funding, under procurement laws.

And the towns must negotiate cable TV licensing agreements, since the Frontier package would include that programming. Cable TV has not been available in the towns.

Such agreements are overseen by the state Department of Telecommunications and Cable, which, in the Frontier case, would be pulled into the last-mile issue, adding a layer of complexity. The deal also appears to require special "home rule" legislation on Beacon Hill.

According to people involved in discussions with Frontier, the company asked for the $1 million premium payment late in the process.

Larkin said the MBI board accepted the additional outlay.

"We've got to bring broadband to these towns," he said.

Donnelly said the Frontier plan offers download and upload speeds of 30 megabits per second (mbps) for $50 a month.

"That's compelling to us, and a pretty competitive price for broadband speed," he said.

Frontier's offer would compel it to match other providers on price within a 100-mile radius.

After 15 years, it would be up to participating towns to decide whether to renew with Frontier, which would own the entire fiber system.

Town support

Officials in the towns are backing the plan.

Jeff Bye, who chairs Sandisfield's Broadband Committee, said the panel is excited by the Frontier offer and praised MBI's help.

He estimated that, for $100, residents will be able to bundle data, phone and high-definition TV programming.

"It's going to present a wonderful opportunity for a lot of folks," he said. "Not too many companies are knocking on our door."

The Frontier plan provides the option for people to obtain basic speeds of 12-mbps download and 2-mbps upload. While that falls well below the federal definition of broadband, the MBI is charged only with providing access to high-speed service, which the deal allows.

People opting for 30-mbps download and upload service would pay $50 in all, but since all premises would have already been assessed a $35 monthly fee, the monthly bill would be for only an additional $15.

Unlike most other towns in the last-mile program, the Frontier network would connect to the internet in Connecticut, not through the MassachusettsBroadband 123 "middle mile" network.

Bye said that while fiber offers the possibility of gigabit download speeds, he does not expect many to opt for them.

"People just do not need that," he said of such speeds. Those who do want speeds above 30/30 "can just keep adding," Bye said.

"We're excited," he said. "We're hoping parties can close this deal and get crews out there working."

The towns will run marketing programs to encourage a high "take rate" for the service.

"We'll go door to door if we have to," he said.

Calculations by Sandisfield's Broadband Committee show that by paying into Frontier's network, rather than building its own, the town would save $5.3 million over the life of the deal.

The panel estimated town costs to build its own network at $8,957,250, compared with the $3,672,000 expense of paying Frontier.

In neighboring New Marlborough, Frontier's basic connection package might prove appealing on cost grounds, according to Richard Long, chairman of that town's Broadband Committee.

Long notes that one unusual aspect of the deal is the basic operating subsidy that the towns will pay to Frontier — $15.5 million in all, over 15 years. Beyond basic service costing $35 a month, residents and businesses will pay additional fees to Frontier.

Still to be determined, Long said, is how Frontier will price its rates when moving to sign up as many customers as possible.

"We don't know what the initial or promotional rates would be," Long said.

Reach staff writer Larry Parnass at 413-496-6214 or @larryparnass.