How to Check Cell Phone Coverage at Your Address Before Switching
Coverage maps are models of outdoor signal, not promises. Here is how to read the FCC map and carrier maps, test a network at home before you port your number, and challenge a map that is wrong.
Every carrier's map looks great from the sales page. Then you switch, and the bars vanish the moment you walk into your kitchen. The fix is to treat maps as a shortlist and to test the network yourself before you move your number.
What "covered" actually means on a map
Coverage maps aren't drawn by hand. FCC rules tell carriers what their filed maps have to represent. For 4G LTE, that's a minimum of 5 Mbps down and 1 Mbps up at the cell edge. 5G is mapped at two levels: 7/1 Mbps and 35/3 Mbps. So "5G" on one layer can mean something quite different from "5G" on another.
The shaded area is where users should expect those speeds with a cell edge probability of at least 90%, with the network at least 50% loaded. That's a model with odds built in. It isn't a promise about your address.
Even the big three have holes. The FCC says none of the nationwide carriers has a truly ubiquitous network, though each reports 4G LTE coverage of at least 95% of the US population and at least 68% of US road miles. If you drive rural roads for work, that road-mile figure matters more than the population one.
Step 1: Look up your address on the FCC map
The FCC's National Broadband Map, at broadbandmap.fcc.gov, displays mobile coverage information that carriers report. Its advantage is that every carrier plays by the same rules. Filed maps must account for terrain and clutter, with a resolution of 100 meters or better.
Search your home address, then your workplace, then anywhere you spend real time: a parent's house, your kid's school, the stretch of highway where calls always drop. Compare each provider on the same technology and speed level. An area shown with 5G at 7/1 Mbps may not show 5G at 35/3 Mbps.
Step 2: Cross-check the carrier's own map
Now open each finalist's own map for the same addresses. Each carrier uses its own labels and colors, so check the legend before you compare.
Read the fine print, though. Verizon's map says it shows approximate outdoor coverage and is not a guarantee of service, and that actual coverage may vary and is subject to change. Assume the same caution applies to any carrier map, whatever the disclaimer says.
If the two maps disagree about your street, don't split the difference. Go test.
Looking at a budget carrier? Check the map of the network it runs on: MVNOs buy service wholesale from a larger carrier instead of running their own towers. Our guide to what an MVNO is explains how that works.
Indoors is the blind spot
Here's the part most people miss. The maps carriers submit to the FCC must depict outdoor coverage: on-street or pedestrian stationary use, and in-vehicle use. Nothing in that definition describes your basement, a steel-framed office or the back bedroom of a brick house.
So the only way to know about indoor service is to try it indoors. If a weak signal at home is the problem, Wi-Fi calling can fill the gap; our guide to using your phone abroad explains how Wi-Fi calling works. It depends on your home internet connection, which is one of the tradeoffs covered in our comparison of VoIP and traditional phone service.
Step 3: Test before you port your number
The cleanest trial keeps your current number where it is and adds the candidate network as a second line, often an eSIM. On an iPhone, Dual SIM lets you have two active phone numbers or SIMs for calls and texts.
There's a catch. To use two different carriers at once, your iPhone must be unlocked by its carrier, or both plans must come from the same carrier. Check first: on the About screen in Settings, General, an unlocked iPhone shows "No SIM restrictions" next to Carrier Lock. If you've never added a second line, our walkthrough on setting up an eSIM covers the steps.
One detail trips people up. Only one number at a time can use cellular data. Before you run any speed test, switch data to the trial line, or you'll be measuring your old carrier.
What to test, and where
- Calls from the rooms you actually use, with the door closed.
- A video call from your desk, and a text with a photo from the basement or garage.
- Your commute, at the time you normally drive or ride it.
- Evenings and weekends, when more neighbors are online.
Jot down the spot, the time and the result in a note on your phone. After several days, a pattern tends to show up. Only then start the port. If you've ever wondered where your number's first three digits come from, see our list of US area codes and the North American Numbering Plan.
If the map is wrong: file a challenge
If your own carrier's FCC map shows coverage you don't get, you can dispute it. Consumers can challenge mobile coverage for lack of service or for poor service quality such as slow speeds. The tool is the FCC Mobile Speed Test app, which replaced the original FCC Speed Test app in July 2024. Tests can go in as formal challenges or as crowdsourced data for the FCC's verification and audit work.
The rules are strict:
- You must be a subscriber or authorized user of the provider you're challenging. You can't challenge a carrier you're only shopping.
- You must certify that the tests were taken outdoors. Tests have to run between 6:00 a.m. and 10:00 p.m. local time.
- Download and upload are scored separately. For 4G LTE, a download result of 5 Mbps or more counts as positive.
- With 20 or fewer results of one type in an area, at least five must be negative. Those negatives must include two sets at least four hours apart by time of day, on any date.
The app's repeated-test mode helps: you don't have to re-enter and certify your details before each run, and it allows hands-free tests while driving. Skip game days, though. A carrier can contest tests taken during an uncommon special event.
Carriers are notified of valid challenges at the end of each month. A carrier then has 60 days to rebut, or it concedes and the area is marked as lacking sufficient service. If it concedes or loses, it has 30 days to file data showing the area that lacks service.
FAQ
How accurate are cell phone coverage maps?
They're models of outdoor service at set speeds and odds, not measurements at your door. Verizon's own map calls its coverage approximate and not a guarantee.
Does the FCC map show indoor coverage?
No. The maps carriers file must depict outdoor coverage, standing still or in a vehicle.
What speed does "covered" mean on the FCC map?
For 4G LTE, at least 5 Mbps down and 1 Mbps up at the cell edge. 5G is shown at 7/1 Mbps and 35/3 Mbps.
Can I challenge a carrier I don't use?
No. Consumer challengers must certify they're a subscriber or authorized user of that provider.
Sources
- Electronic Code of Federal Regulations (eCFR): 47 CFR 1.7004 Scope, content, and frequency of Broadband Data Collection filings (accessed 2026-09-24)
- Federal Communications Commission: 2024 Communications Marketplace Report (FCC 24-136, released December 31, 2024) (accessed 2026-09-24)
- Federal Communications Commission: FCC Launches New Mobile Speed Test App (press release, July 23, 2024) (accessed 2026-09-24)
- Verizon: Coverage Map (accessed 2026-09-24)
- Apple Support: Using Dual SIM with an eSIM (accessed 2026-09-24)
- Apple Support: How to unlock your iPhone for use with a different carrier (accessed 2026-09-24)
- Electronic Code of Federal Regulations (eCFR): 47 CFR 1.7006 Data verification (accessed 2026-09-24)