Cell phone GPS question

I’ve been traveling around the Lesser Antilles and I’m about to head to Colombia. Until now I haven’t had to rely on my phone’s GPS on land but now that I’ve started driving and planning to do more of it in South America, it proves to be unreliable; it cuts in and out, mostly out. I’m told that I need to get a local sim card to solve the problem. My question is this: how is my US phone GPS dependent on the sim card whereas a standalone unit on the boat works regardless of position on the planet? Do the phone service providers pay google maps a user fee that restricts the coverage to the US?

Is it the GPS that’s unreliable or the maps? Maybe you need local internet to have the maps available to see where the GPS has you.


Maps.me works offline.


I am pretty sure the GPS works regardless of whether you can connect via the sim card carrier. What I have done without a local sim card and to avoid roaming charges is to download maps in advance from Google. They will work with the phone’s GPS even if you don’t have a local sim or connectivity by your own carrier. The phone’s GPS worked with the downloaded maps without connectivity to a network.

The above also works to minimize data usage if you have connectivity. A burner sim card might have data limits.

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What’s cutting in and out, the GPS signal?

Your response is correct. After I posted, and before buying a local sim card that would only be used for a short time, I was shown that downloading the map from Google solves the problem.

@Capt_Phoenix - The GPS signal did not seem to be interrupted but the depiction of the map would disappear, sometimes by sections or completely, and replaced by a grid pattern.

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your app is scamming you to force money to be spent with the telco, thats how the phone industry works

I’ve had the same issue using map apps also. I try to remember to download the maps when I have WIFI. I’ve gotten unexpectedly hit for roaming charges a couple of time from app automatically downloading maps.

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Your cell phone does not have a satellite GPS receiver.

It uses cell tower information to provide the position of your phone relative to same. This translated onto a map. Hence why your cell phone won’t give you a position in mid-ocean.

If you really want or need GPS, buy a handheld GPS receiver.

Problem solved.

UPDATE - After reading a bit on the topic it is clear the above is wrong. There are GPS chips in some cell phones. Exactly what functionality is provided appears to vary.

Still, a good Garmin handheld receiver will certainly be useful in remote areas of S Amurca

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Apparently a combination of both:
How Assisted GPS Works in Cellphones.

many phones have gps chips.
Have held my to an aircraft window and got speed.
Its std gps so any app can use it

Yes. This seems to be the case.

Maps.me, free, download the maps ahead of time, it will track your movements, drop pins, if you tell it to do so.

I had a mate who insisted this was true until I took my phone onto the bridge wing in the middle of the ocean to show him that it does, in fact, give the position.

The GPS in my iPhone works everywhere with or without cell signal.

If maps.me has been downloaded on Wi-Fi for the area that I’m in, even if no cell signal, that works too.

In Europe, I usually buy cheap prepaid Orange SIM cards (they work in many countries).

In Latin America, I usually buy cheap prepaid Claro or Movistar SIM cards.

T-Mobile is the cheapest and 2nd best USA SIM card for travel. My experience has been that it’s getting worse. AT&T has the best and most reliable service, but is very expensive.

In some localities only one particular SIM card works. In most places, some SIM cards work better that others.

Foreign prepaid SIM cards a very cheap compared to what we normally spend for phone service in the USA.

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When my Garmin bit the dust I replaced it with a Dual XGPS receiver. It connects to a phone with Bluetooth.


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Thanks for the tip. Maps.me is more user friendly than downloading google maps.


I’ve got an iPad that is wi-fi only (no cellular connection). It’s an iPad Mini which is really a nice size for a portable GPS/Map. I’ve used it quite a bit outside the US for driving Nav., mostly in Europe. How I connect is: I have a tiny little GPS called a “Bad Elf” that a pilot friend of mine introduced me to. I guess a lot of guys use them for flying in light sport planes, etc. that don’t have fancy built-ins in the panel. The Bad Elf is super fast and accurate and used both the US and Russian system satellites for tracking. My iPad has an App that receives the Bad Elf GPS fix and transmits it to the iPad’s location function (which otherwise just uses cell-tower triangulation for a rough fix…yes, at least as I have been told, even w/o the cellular function, wi-fi only iPads use cell tower [and known wi-fi router] fixes for their location; apparently even if you don’t buy the cellular function, Apple wants to be able to track you and sell your location to it’s marketing data customers!). Once you’ve got your GPS location available in the iPads system, you can use any onboard map. You can pre-load Google Maps. I’ve found a driving nav program that has world-wide coverage and really good driving maps for Europe that is called Co-Pilot GPS. Co-Pilot’s maps are downloaded in groups as you wish: states, nations, regions, continents, so you can have all the maps you might want in one download, which is a lot more convenient than doing it with Google Maps. Costs some $ of course, but their maps are pretty reasonable and kept pretty up-to-date. Just FYI re one method for handling the no wi-fi signal/no cellular signal plan on a phone (or iPad). Not sure about S. America/Caribbean, but generally Co-Pilots map availability for other than US/Europe is as best I recall, pretty good. And the maps themselves are very good graphically for quick looks while driving.

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So maps.me was easy to download, with various parts of the world grouped together. Within a minute of leaving base with wifi however, the map started spinning like a top. Next time I drive, I’ll try the downloaded google map and see how that works out before resorting to a sim card or other solution.