The two carriers were the largest players that signed on to a detailed set of specifications for boosters, which are two-way radios that amplify cellular coverage in a building or vehicle. The devices are largely unregulated today, but the proposed rules could introduce new requirements for users.

The specifications emerged from a lengthy launched last year and from technical work to narrow down the proposals, said Joe Banos, chief operating officer of Wilson Electronics, which makes boosters and has been pushing for Federal Communications Commission rules on them for years. He thinks there is a good chance the FCC will approve the rules, with little or no modification, within 90 days.

"I think we're close to the end of the road," Banos said on Monday. After the commission's vote, the industry would have to settle on procedures for compliance testing, which might take six months, he said. At some point after that, products would be tested and boosters that didn't comply would have to be removed from sale.

In a June 8 letter, Wilson, two other manufacturers and the two carriers told the FCC they had agreed on a set of rules that would govern all boosters. Those include devices being able to shut down or reduce their power to prevent interference with a carrier's signal, plus a rule that consumers have to notify their carrier before they can use a booster.

However, the letter said the companies couldn't agree on whether consumers should have to ask their carrier's permission to use a booster. Instead, they would make their views known to the FCC separately, it said.