Wireless carriers reported some progress reversing the widespread service outages the plagued much of Napa County as massive wildfires surged through the North Bay this week, disabling cellular transmitters and the power lines that sustain them.

Verizon Wireless repair crews have restored 98 percent of network coverage in areas in the path of wildfire in Napa, Sonoma and Mendocino counties, according to regional president Jonathan LeCompte.

In Napa, Verizon has deployed a disaster response trailer at Kaiser Permanente medical office at 3285 Claremont Way, with Internet access, laptop computers, phones and a cellphone charging station for public use.

Additional wireless connectivity to support emergency workers has been added to the Napa County Sheriff’s Office and the Cal Fire base camp in Napa, LeCompte said in a press release.

AT&T Mobility has restored more than 99 percent of its wireless service in the North Bay, but certain areas remain impassable or too dangerous to enter due to high wind warnings and the possibility of fire flare-ups, according to spokesman Leland Kim. The carrier has rolled out mobile cell transmitters to stand in for towers damaged in Yountville and Calistoga, as well as parts of Santa Rosa, he said Thursday.

While swaths of Napa Valley forests remain ablaze and off limits, wireless carriers are temporarily patching their coverage holes with wheeled transmitters, which run on generators and do not need an electrical connection in areas still without power.

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Sprint has restored wireless service to various parts of Napa County, “but there are a few more sites that are still inaccessible and cannot be serviced until evacuation orders are lifted,” said spokesman John Votava. The carrier has extended its waiver of voice, data and text overage fees in fire-stricken communities through Sunday, he added.

T-Mobile US Inc. reported that the carrier also had restored coverage to most fire-affected areas by Thursday, as well as deploying portable antenna stations into the North Bay.

All four major cellular carriers reported widespread loss of service after multiple blazes broke out Sunday night and consumed tens of thousands of acres. Repair crews were not immediately able to tend to affected towers because of extensive power failures caused by the fires, as well as roadblocks cutting off areas under mandatory evacuation orders.

Flames cut off a fiber-optic cable that passes data and voice calls to and from several Napa-area cellular towers, Sprint reported earlier. Calls, text messages and Web traffic pass from handsets to the towers, through cables and on to switches called local exchange carriers, which route traffic to other users.