Given a path on some navigation program such as Google Maps or Waze in the United States, how can I know ahead of time (= before driving) whether some parts of the path are not covered by cellular network (i.e., not possible to make phone calls or access Internet)?

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    I remember when driving in Arizona, Google Maps suggested me to download navigation instructions due to poor connection along the route. Of course you can also manually download offline maps and navigate offline. This does not answer your question in a meaningful way, but I feel my comment can still help others.
    – Bernhard
    Commented Jan 3, 2021 at 9:11
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    Surprisingly, I-40 through Arizona has some atrocious coverage areas, not even counting local topography that impacts many parts of the US West...
    – Jon Custer
    Commented Jan 3, 2021 at 17:16

1 Answer 1


Your best bet is to look up the coverage map for your carrier. The major carriers (AT&T, Verizon, Sprint/T-Mobile) all have maps, and you can look at your planned route and see what the coverage is supposed to be along the way. I'm not aware of any automated way to integrate this process with a navigation program.

The reality though is that these maps aren't all that accurate and often overstate the actual coverage. I'd use them to get a general idea of what to expect—if the area you're in shows no coverage, then I'd expect no coverage—but not as any real assurance that you'll have coverage everywhere indicated on the maps.

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    Its also worth noting that cell tower coverage doesnt actually mean service is available - towers have a certain number of frequency slots available, and preference is given to stronger signals, so your phone may show bars (which is done on the control channel, same as SMS) but still never be able to make a call or browse the internet as your phone cant get frequency slots...
    – user29788
    Commented Jan 3, 2021 at 6:47
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    I guess you could also experiment with crowdsourced coverage info from e.g. OpenSignal or CellMapper but I haven't used either of them enough to know if they're particularly reliable.
    – mlc
    Commented Jan 3, 2021 at 7:00
  • It may be worth noting that nowadays carriers use different frequencies for different technologies in different places, and not all phones support all frequencies, especially if one doesn’t use a phone that was specifically sold by/for that carrier, and of course international phones. On the other hand, when roaming with a foreign phone, one often has access to multiple locally carriers. And of course, not all phones are made equal.
    – jcaron
    Commented Jan 3, 2021 at 13:10
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    I found these maps to be mostly useless. My house has supposed to have "excellent coverage" and all our phones get two bars at best on a good day and sometimes none at all. So it may be able to tell you where you are guaranteed to have NO coverage, but it doesn't tell you anything about whether you have usable coverage or not.
    – Hilmar
    Commented Jan 3, 2021 at 13:51

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