iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
A landline may or may not work during a power outage. The answer depends on how the provider delivers the voice service. Traditional copper POTS lines usually receive power from the provider’s central office and can keep working with a corded phone. Fiber, cable, and internet-based phone services normally require electricity for equipment inside your home, such as an optical network terminal (ONT), modem, gateway, or cordless-phone base.
A battery or UPS can keep that equipment running for a limited time, but it does not guarantee that the provider’s wider network, upstream facility, internet connection, alarms, medical devices, or every handset will remain available. Identify the technology and equipment in your own service before relying on it in an emergency.
“Landline” describes the phone, not the network
People use landline to mean a phone number and handset tied to a fixed address. The word does not identify the underlying network. A fixed phone can use an old copper pair, a fiber connection, a cable operator’s voice network, or voice-over-IP (VoIP) equipment. Each arrangement has different power requirements.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problems| Delivery method | What carries the service | Equipment that may need household power | Typical outage concern |
|---|---|---|---|
| Traditional copper POTS | An electrical signal on a copper telephone pair from the provider’s central office | Usually no in-home network device for a corded phone; a cordless base still needs power | Often continues locally during a power failure, but not guaranteed against every network failure |
| Fiber-delivered voice | Optical signals on a fiber cable | ONT and, depending on the design, a gateway, modem, or other adapter | Voice stops when a required device loses power unless compatible backup power is working |
| Cable voice | The cable operator’s access network | Usually provider equipment such as a powered modem or voice gateway; the exact path varies | Depends on the premises equipment, backup arrangement, and the provider’s network |
| Internet-based VoIP | Voice packets carried over a broadband connection | Every device in the voice path, including a modem, router or gateway, phone adapter, and cordless base | A local outage can remove both the broadband connection and the phone service |
The service label on your bill or the fact that you have a number that “looks like a home phone” is not enough to predict outage behavior. Ask which delivery method you have and trace the equipment connected to the phone jack.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
How the main landline technologies get power
Traditional copper POTS
Plain old telephone service (POTS) uses a copper pair that normally carries line power from the telephone company’s central office. The central office generally has batteries or generators, so a simple corded telephone can continue to receive power when the home’s electrical service is off. California’s Public Utilities Commission says copper POTS customers will generally have service during a power outage, and Vermont’s Department of Public Service describes the same central-office power arrangement.
“Generally” is important. A damaged cable, flooded cabinet, failed central-office system, deliberate de-energization, or a broader provider outage can still interrupt a copper line. Central-office power protects the line from a loss of electricity at your house; it cannot make the entire network indestructible.
A cordless phone changes the result. Its handset communicates with a base station that plugs into an electrical outlet. During an outage, the copper pair may still be live while the cordless base is dead. Keep a basic corded phone available if you want to use the copper line without household power.
Fiber-delivered phone service
Fiber carries pulses of light, not the electrical power needed to operate the devices at the customer’s premises. The ONT converts the optical connection into electrical interfaces for voice, data, and other services. If the ONT loses power, the phone service connected through it normally loses its path.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Some providers put voice directly through the ONT. Others route it through an additional gateway, modem, or voice adapter. Every required device must remain powered. Verizon explains that its Fios services require an electrically powered ONT, while Fidium says its fiber voice service will not work without a working backup when premises power is lost.
Do not assume that powering the ONT powers everything else. A separate router, Wi-Fi system, cordless base, alarm communicator, or medical device may have its own power supply and may not be connected to the same backup.
Internet-based voice and VoIP
VoIP converts speech into data and sends it through network equipment. The Federal Communications Commission’s 2015 order (FCC 15-98) describes analog telephone adapter functionality embedded in devices such as fiber ONTs. In a household installation, the voice path can include a modem, gateway, router, ONT, phone adapter, and handset.
Windows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallCrashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteAT&T’s battery-backup guidance specifically lists gateways, modems, and ONTs and warns that cordless-phone equipment may also require power. A backup that keeps one box running is useful only if every other required link remains available. Service also depends on the provider’s underlying network and facilities, not just on the equipment in your home.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
What happens when the power fails?
Use the following sequence to determine what you can expect before an outage.
- Identify the access cable. A copper telephone wire entering a telephone jack suggests POTS. A fiber strand terminating in an ONT, or a phone jack on a modem or gateway, indicates a powered service. If you are unsure, ask the provider to name the voice technology on your account.
- List every device between the network and the handset. Write down the ONT, modem, gateway, router, phone adapter, and cordless base. A device that the provider supplied but that you do not use for internet access may still be essential to voice.
- Check the handset type. A corded phone can draw power from a copper POTS line. A cordless handset cannot operate without its base station, even when the telephone line itself is working.
- Ask about supported backup power. Get the exact battery or UPS requirement for your equipment, the connector or outlet to use, the stated runtime, and whether the figure applies to voice only.
- Plan a second way to communicate. A mobile phone, another fixed line on a different network, or a charged battery-powered communication device can cover a provider or facility failure that a home UPS cannot.
If the local outage is the only problem and all required premises equipment is on a compatible, charged backup, a fiber or VoIP line may continue for the backup’s rated period. If the provider’s facility, neighborhood equipment, backhaul, or emergency systems also lose power or connectivity, the line can fail even while your ONT or gateway remains on.
What backup power can—and cannot—keep running
Backup power is a way to run specified premises equipment during a local electrical failure. It is not a universal substitute for the electrical grid and it is not automatically sized for every connected device.
The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →| Published example | Configuration and stated duration | What the figure means |
|---|---|---|
| Verizon Battery Backup Unit | Up to 8 hours of basic voice service when a Battery Backup Unit is installed with the ONT and a 12-volt battery is used; Verizon support guidance accessed in 2026 | A provider-specific voice runtime, not a guarantee for internet, TV, cordless handsets, or peripherals |
| Verizon PowerReserve | At least 24 hours of basic voice service using 12 fresh D-cell batteries with a compatible ONT power adapter; Verizon support guidance accessed in 2026 | Applies to the specified PowerReserve and ONT arrangement; it does not establish a 24-hour standard for other installations |
| Fidium Fiber battery arrangement | Up to 24 hours powering the ONT with three eight-hour batteries | An example for Fidium’s equipment and configuration; the provider warns that backup may not sustain every service through a particular outage |
These durations are not population statistics and are not interchangeable. Battery age, temperature, load, the number of devices connected, and the provider’s design affect actual runtime. “Basic voice service” generally does not mean that broadband, Wi-Fi, television, security systems, medical alert equipment, accessibility devices, or cordless phones are also powered.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
When a UPS is appropriate
A customer-supplied uninterruptible power supply can be a reasonable option when the provider confirms that the ONT, gateway, modem, or adapter can use it. Match the UPS output and capacity to the device’s specifications, and verify which equipment must be connected. Do not select a model solely because it has enough outlets or a large battery rating.
Ask the provider whether a third-party UPS is supported, whether a provider battery is required for service or emergency calling, and how the runtime was calculated. A UPS can preserve electricity at your wall outlet; it cannot restore an upstream provider facility, neighborhood node, fiber break, or internet route.
What the backup will not cover automatically
- Internet access, Wi-Fi, or television equipment that is not connected to the backup.
- A cordless phone’s base station or any additional handset charger.
- Alarm panels, medical alert systems, elevator phones, fax machines, or accessibility equipment unless their makers and the provider confirm compatibility.
- Provider-side equipment, central offices, fiber nodes, cable hubs, wireless backhaul, and other facilities outside your home.
- Any device whose battery is depleted, disconnected, incompatible, or too small for the electrical load.
How to prepare before an outage
Document the voice path
Take a photo of the ONT, modem, gateway, and phone connections. Record model numbers, indicator labels, the provider’s support number, and the battery type. Mark which outlet or power strip feeds each device. This prevents a well-intentioned helper from unplugging the phone equipment while trying to conserve electricity.
Free tools Windows power users keep installed
One-click scans. No signup required.
Keep a corded handset if you have copper POTS
Store a working corded phone where it can be connected directly to the telephone jack. Test it periodically by unplugging the cordless base from the wall. If the corded handset has no dial tone, the problem may be outside the home even though the outage began locally.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Test the backup under realistic load
With the provider’s instructions, connect the required equipment to the backup and confirm that the phone can place and receive a call. Check whether the test leaves internet, Wi-Fi, or other services running; do not infer their availability from a successful voice call. Replace batteries according to the provider’s schedule and before a forecast outage.
Protect critical users
Anyone who relies on a medical alert system, monitored alarm, emergency call button, elevator phone, or accessibility device should ask that device’s supplier and the telephone provider how it behaves without utility power. A phone that works for ordinary calls may not keep those systems connected.
Troubleshooting during a power outage
The phone is dead immediately
- For copper POTS, plug a corded phone directly into the wall jack and disconnect the cordless base. If there is still no dial tone, report a line or network problem.
- For fiber or VoIP, check whether the ONT, modem, gateway, and phone adapter are connected to the charged backup. A missing device in the chain can stop voice.
- Do not repeatedly unplug and reconnect equipment if the provider’s instructions warn against it; preserve the remaining battery for a controlled call to support or emergency services.
The backup is on, but calls still fail
Power at the ONT or gateway does not prove that the provider’s network is operating. The outage may affect an upstream facility or the connection beyond your premises. Use another communication method to check for a provider outage and to contact emergency services if needed.
Only the cordless phone fails
Try a corded handset on a copper POTS line. On a fiber, cable, or VoIP service, connect the cordless base to the backup only if the provider says that load is supported. Otherwise, the base may consume runtime intended for the voice equipment.
Service does not return after utility power
Confirm that each device has restarted and that the backup has not switched off or exhausted its battery. If the equipment appears powered but the phone remains unavailable, treat it as a possible provider-side fault and report the exact devices and indicators to support.
Questions to ask your provider
- Is my voice service delivered over copper POTS, directly through an ONT, through a modem or gateway, through cable equipment, or as another form of VoIP?
- Which exact devices must remain powered for incoming and outgoing calls?
- Does my installation include a provider battery, and what battery type and replacement schedule apply?
- Is a customer UPS supported, and where should it be connected?
- What runtime do you specify for this equipment configuration, and is that runtime for basic voice only?
- Will internet, Wi-Fi, television, alarms, medical alert equipment, accessibility devices, and cordless handsets remain available?
- Does your outage guidance depend on power at an upstream facility or other network location?
- Are emergency calls, including 911, subject to any additional limitations during a power or network outage?
The practical answer
If your “landline” is traditional copper POTS, a corded phone will generally continue during a household power failure because the central office supplies line power. If the service uses fiber, cable equipment, or internet-based VoIP, expect the ONT, modem, gateway, adapter, and possibly the cordless base to need household electricity. A compatible backup can extend voice service, but its duration and scope are specific to the provider’s equipment and do not cover failures elsewhere in the network.
Confirm the technology, map the equipment, test the approved backup, and keep an independent communication option available. That is the only reliable way to know what your particular fixed phone will do when the lights go out.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
