As Hurricane Florence barrels toward the Carolinas, the nation's top four wireless carriers are preparing for the worst.

The storm, now a category 4 hurricane, is expected to bring "life-threatening storm surge and rainfall" to portions of North Carolina, South Carolina, and surrounding mid-Atlantic states in the coming days, according to the National Hurricane Center. Maximum sustained winds near 130mph, with even higher gusts, are expected. The center of the hurricane is projected to move over the Atlantic Ocean between Bermuda and the Bahamas today before approaching the US on Thursday and Friday.

"While some weakening is expected on Thursday, Florence is forecast to be an extremely dangerous major hurricane when it nears the US coast," the National Hurricane Center said this morning.

9/12 11:00 AM EDT: Here are the Key Messages for #Hurricane #Florence. The full advisory is at: https://t.co/tW4KeGdBFb pic.twitter.com/HQ5pqRroGs — National Hurricane Center (@NHC_Atlantic) September 12, 2018

If you live near the Southeast Coast, be sure to follow safety orders from local authorities. If you plan to hunker down, keep your devices in waterproof cases or at least re-sealable plastic bags.

"We saw a lot of people who fortunately made it through the flood waters of Hurricane Harvey last year, but their phones didn't," Sprint said in an email to PCMag.

Be sure to keep your device fully charged just in case you lose power. During and after the storm, texting may be your best bet instead of calling due to possible network congestion. Also, store emergency numbers in your phone, download the American Red Cross Hurricane app and FEMA app, and gather extra batteries and car chargers.

Meanwhile, here's what the mobile carriers are doing to prepare.

Verizon

In an email to PCMag, Verizon said it's readying a fleet of mobile equipment—including Cells on Wheels (COWS, pictured below), Cells on Light Trucks (COLTS), and generators on a trailers (Goats)—which can be rolled into hard-hit areas in need of extra network capacity.

The carrier says it has secured enough fuel for mobile units and generators to keep its network up and running "at full strength even if commercial power is lost for an expended period of time." The Verizon Response Team is also readying charging stations and disaster response trailers, which will be deployed "where the need will be greatest."

Verizon is coordinating with local, state, and federal emergency services to ensure they will stay connected. The company also lifted all speed cap restrictions for first responders in North Carolina, South Carolina, and Virginia. After the storm, Verizon will use drones to survey tower damage.

AT&T

AT&T on Tuesday said it will provide unlimited talk, text, and data to customers—including prepaid users—"in areas most affected by Hurricane Florence."

"We are closely monitoring Hurricane Florence, and we're committed to taking care of our customers in their time of need," the carrier wrote.

AT&T has been "topping off fuel generators" and "testing high-capacity back-up batteries at cell sites." The carrier is using sandbags to protect its physical facilities against flooding and has been staging emergency response equipment to be deployed after the storm.

In addition to mobile cell sites and command centers like COWS and COLTs, AT&T may use portable cell sites on drones, aka Flying Cell on Wings (or Flying COWS), to provide wireless connectivity to customers in hard-hit areas. The company first deployed Flying COWS in Puerto Rico last year in the wake of Hurricane Maria.

Sprint

Sprint is taking similar precautions. The carrier said its crews are fueling fixed and portable generators that will be used in the event of expected commercial power outages. The company is also staging emergency vehicles across the Carolinas that will provide additional wireless capacity in impacted areas, if necessary.

Sprint said it's ready to deploy incident management teams to assess the damage, inspect its wireless networks, and make repairs. Like Verizon, Sprint plans to use drones to help assess damage after the storm.

"Our teams are working around the clock and have been closely monitoring the storm in an effort to keep our customers connected once Florence makes landfall as expected," Sprint said in an email to PCMag. "We know how important wireless service is because as it's the lifeline when communications is needed during major weather events. That's why our network teams began preparation days ago and stand ready to deploy incident management teams, assess impacted areas, inspect local wireless networks, and make any repairs if needed after the event."

T-Mobile

T-Mobile says its engineering and rapid response teams are ready to activate emergency equipment such COWS, portable generators, and more "as soon as the storm begins to impact the area." Still, the carrier warned that expected tree damage, power outages, and flooding could result in network outages.

T-Mobile stores will remain open "as long as it's safe," the company said. "They will have water, mobile generators, device charging stations, car and wall chargers and other supplies available."