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Does internet work during a power outage?

By Roof & Router Team. Updated November 3, 2026.

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Does internet work during a power outage?

Usually not, at least not on its own. Home internet runs through boxes that plug into the wall:

• A modem for cable internet.
• An ONT (optical network terminal) for fiber. T-Mobile describes it as the device at the end of the fiber line that turns light signals into data your home network can use. It is an active device and needs electricity.
• A Wi-Fi router, which is sometimes built into the modem as a “gateway.”

When your home loses power, those boxes shut off and Wi-Fi goes with them, even if your provider’s network outside is fine. The FCC put it plainly in its 2015 backup power order: “modern fiber and cable networks do not provide power to operate necessary equipment at the subscriber location.” Old copper landlines were different. Fairfax County’s cable office notes that copper phone service gets its power from the phone company and keeps working as long as the central office has power.

So the real question is whether you can keep those boxes powered, and whether your provider’s network still has power.

Why does Wi-Fi go down when the power goes out?

Your phone and laptop have batteries. Your modem, router and ONT do not. Fairfax County says cable and fiber internet stops unless the modem and router have power, and fixed wireless home internet, such as T-Mobile’s, also stops unless its modem and router are on a UPS (uninterruptible power supply) or generator.

A phone battery backup from your provider usually does not fix this:

• Verizon Fios: “Backup power does not support Internet or TV service during an outage.” Its battery gives up to 8 hours of backup for voice, including 911.
• Xfinity Voice: its battery backup keeps the phone line and alarm system running for up to 24 hours, Xfinity says, and only the primary phone number works during an outage. The page does not say it powers internet.
• AT&T: its battery kits power the Wi-Fi gateway, but AT&T warns that internet use “will quickly drain your stored power” and says to limit use to emergency calls.

Does internet work if only my house loses power?

This is the best-case outage. If a breaker trips, or a tree takes down only your service line, your provider’s network is probably still powered. Keep your modem, router and ONT running on a UPS or power station and you stay online.

An area-wide outage is harder. Your internet then also depends on the provider’s equipment in your neighborhood having backup power. None of the provider pages cited here say how long that equipment lasts. Comments cited in the FCC’s 2015 order said restoring power took 12 days after Hurricane Sandy and 15 days after Katrina, far longer than most backup batteries are built for.

Xfinity’s own backup product hints at this. Its Storm-Ready WiFi extender switches to a 4G LTE cell connection when the gateway goes offline from a network outage, at speeds up to 30 Mbps down and 7 Mbps up. With an optional $60 battery, it can also run “for up to four hours during a power outage when fully charged.”

Fiber and cable behave the same way at home: both need power. See fiber vs. cable internet for other differences.

How long does internet last during a power outage?

How long can a UPS keep a modem and router running?

Start with the load. ARRIS lists its SURFboard SB6141 cable modem at 12 W nominal. EnergySage says most Wi-Fi routers use 5 to 20 W and calls 10 W a safe average. Together that is about 22 W. Your gear may differ, so check the labels; see how much electricity a Wi-Fi router uses.

APC’s datasheet for its 600VA/330W Back-UPS BE600M1 lists:

• 10 W (“modem + router”): 4.3 hours
• 40 W: 67 minutes

Our math: 10 W × 4.3 hours = 43 Wh delivered. 40 W × 1.12 hours = about 45 Wh delivered. So this UPS gives roughly 44 Wh of usable energy at light loads. At 22 W: 44 Wh ÷ 22 W = about 2 hours.

The larger BE850M2 is rated 5.9 hours at 10 W, about 59 Wh. At 22 W that is about 2.7 hours, our estimate. For comparison, CyberPower lists its 600VA/340W CP600LCD at 13 minutes at half load and 2 minutes at full load, which shows how fast runtime falls as you add devices. Plug only the modem, router and ONT into the battery outlets.

For sizing a UPS for more devices, see what size UPS battery backup you need.

Need more than a few hours? A portable power station holds far more energy. Our math: a 1,000 Wh station, assuming about 15% lost to its inverter (it varies by model), gives about 850 Wh. 850 Wh ÷ 22 W = about 39 hours. See what a 1,000Wh power station can run.

Do fiber and VoIP home phones have backup power rules?

They did. In 2015 the FCC adopted backup power rules for home phone service that is not powered by the line, which covers phone service over fiber, cable and fixed wireless. The rule, later numbered 47 CFR 9.20, required providers to:

• Offer new customers at least one backup option with a minimum of 8 hours of standby power.
• Also offer an option with a minimum of 24 hours of standby power starting February 13, 2019.
• Tell customers at sign-up and every year about backup options, cost, expected run time and how to test the battery.

Two limits matter:

1. It covered voice, not internet. The FCC said this backup power “will not also power services other than voice.”
2. It was temporary. The FCC limited the obligations to ten years, and the rule text said it would stop being in effect on September 1, 2025. The current version of section 9.20 now covers 911 reliability certifications and has no backup power requirement.

Providers still sell backup. Verizon offers an 8-hour Fios voice battery, and Fairfax County says Verizon’s newer D-cell tray gives 20 hours of talk time or 25 hours of standby. AT&T sells 4-hour and 24-hour kits. If you rely on a home phone for 911, medical alerts or an alarm system, ask your provider what is available. AT&T also warns that many cordless phones need power to make calls, so keep a corded phone if your service supports one.

Do cell phones work during a power outage?

Usually, for a while. Fairfax County says cell towers have backup power that may last many hours, but not indefinitely, and that networks can get overloaded when many people in one area use them at once.

The FCC’s advice for outages:

• Text instead of calling when you can. Texts may get through when calls cannot.
• Do not keep redialing a failed call. It adds to congestion. Try a text instead.
• Keep calls brief and call 911 only for emergencies.
• Save battery with power-saving mode, and charge your phone before a storm. The FCC suggests a spare battery and a car charger.
• Never charge a phone in a running car inside a garage. The FCC warns about carbon monoxide.

Can you use your phone as a hotspot?

Yes. A hotspot shares your phone’s cell data with a laptop or tablet over Wi-Fi, Bluetooth or a USB cable.

• iPhone: Settings, then Personal Hotspot, then turn on “Allow Others to Join.” Apple says your carrier must support Personal Hotspot and fees may apply.
• Android: swipe down and tap the Hotspot tile. Google says some carriers limit or charge extra for tethering.

Hotspot use drains your battery, and Google advises keeping devices plugged in while tethering. A power bank helps. Turn the hotspot off when you are done.

Does Wi-Fi calling work in a power outage?

Only if your home internet is still up. Wi-Fi calling sends calls over your Wi-Fi network, so when the modem and router lose power, your phone has to fall back to the cell network. If your home has weak cell signal, a UPS on your network gear keeps Wi-Fi calling working through short outages. See what Wi-Fi calling is and how it works.

What to do when the power goes out: checklist

Before an outage:

1. Put the modem, router and ONT on a UPS. Check that each one is in a battery outlet, not a surge-only outlet.
2. Ask your provider whether your home phone has a battery backup and how long it lasts.
3. Charge phones and power banks before a storm, as the FCC advises.
4. Save your provider’s outage page and your utility’s outage number in your phone.

During an outage:

1. Unplug anything non-essential from the UPS to stretch runtime.
2. If Wi-Fi drops but the UPS is on, the problem is probably the provider’s network. Switch to your phone’s cell data or hotspot.
3. Text rather than call, and keep calls short.
4. Never charge phones in a running car inside a garage, because of carbon monoxide.

For the rest of your outage plan, from food to heat, see winter power outage preparation.