AT&T says it developed a new way to offer broadband Internet service over utility electric power lines, a once hyped idea that fizzled out over the past decade.

But in a briefing with reporters on Tuesday, AT&T executives said they had learned from prior failures and developed a wholly new technique that resulted in low cost, high speed transmissions. AT&T said it would soon announce market trials of the system, called Project AirGig, with commercial deployment about three to five years away.

Without revealing too much detail about how their new system worked, the executives said the crucial difference was that they were not encoding and transmitting information inside the electrical currents flowing through power lines.

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Instead, the new technique – backed by over 100 patents – sends information alongside the lines using attached plastic antennas. That allowed AT&T t to use more common wireless technologies and operate in standard airwave frequency bands.

“Broadband over power line was basically using the actual conductor itself and these were in very low frequencies,” Andre Fuetsch, president of AT&T Labs, explained. Coping with various elements of the electrical infrastructure also increased costs, he said. “But probably more importantly they couldn’t get the speeds out of that technology that they we’re seeing today. We can actually deliver in the gigabit range.”

AT&T also said the technology was at a fairly advanced stage of development, with all of the needed components ready to go. “We’ve had it up and running… for quite some time now,” John Donovan, chief strategy officer for AT&T, said at the briefing. “And we’re saying that we’re ready to move into the field.”

As early as 2004, the Federal Communications Commission passed rules intended to promote broadband over power lines as a serious challenger to monopoly cable and telephone providers. But the frequencies involved interfered with some radio signals, power utilities never got excited about the technology and costs soared. 

In 2008, a court struck down the FCC’s rules and by the time the agency had a revision ready in 2011, the technology had been surpassed by less complicated wireless technologies. 

Once ready to be fully deployed, AirGig could make it cheaper and easier to bring broadband connectivity to more remote areas that already have electricity wires. The technique could also be used as part of AT&T’s efforts to improve coverage in its existing 4G network or upcoming 5G network.