GPS still works when you travel abroad and it does not inherently require data roaming. Your phone receives navigation signals independently of your mobile carrier. What roaming controls is the internet connection used to download online maps and upload location records for live sharing.
Navigation satellites do not care which mobile network your phone is registered on. If the device has a usable GNSS receiver and can see enough satellites, it can calculate a position in another country without purchasing roaming data.
This is why offline navigation and route logging can be useful while travelling. The main preparation is making sure the maps and application components you need are already on the device.
With roaming data disabled, a tracker cannot normally send new points through the foreign cellular network. It may still record them locally. When the phone reaches hotel Wi-Fi, a hotspot or another approved connection, an offline-capable app can synchronize the stored route.
The remote viewer will see a stale last point until that happens, so do not promise someone “live tracking” when your travel plan intentionally contains long periods without internet.
If you use a navigation application, download offline maps for the countries or regions you will visit. A phone can have an accurate coordinate and still show an empty background if the map tiles were never cached.
Also download language packs, tickets and important travel documents that you may need without connectivity. GPS is only one part of an offline travel setup.
If live LocationOf updates matter, a travel eSIM or local data plan can provide the network path without relying on expensive home-carrier roaming. Compare coverage and data terms for the actual countries you will visit. GPS use itself is not what consumes the allowance; uploads and map traffic do.
If the device has no SIM at all, read GPS without a SIM card.
A tracking system should store an unambiguous time reference and display it consistently. When travelling through time zones, distinguish the time a point was captured from the local clock displayed to the viewer. A route should not appear to move backward in time merely because the user crossed a border or changed the phone's time zone.
When reviewing a trip later, keep this in mind if comparing the tracker with photos, tickets or messages that use local time.
Poor cellular signal can increase power consumption because the modem works harder to maintain service. Bright screens, navigation, photography and hotspot use may consume more power than the location logger itself. Carry a suitable charger or power bank and measure the whole travel setup rather than attributing every percentage point to GPS.
If that works at home, you understand how the setup should behave when roaming is unavailable abroad.
LocationOf can only show the server the records that reach it. International travel does not change the basic model: the phone determines location and a network transports the record. Use Wi-Fi-only synchronization if that is sufficient, or arrange data connectivity when viewers need current points.
For the underlying distinction, read Does GPS use mobile data?.
Travellers often depend on hotel, airport and café Wi-Fi when roaming is disabled. Use the current LocationOf Android build and HTTPS website so credentials and precise location are not intentionally sent over plain HTTP. Avoid installing certificates or “helper” applications offered by unknown networks.
A captive portal can also make a phone look connected to Wi-Fi while internet access is not actually available. If queued location points do not upload, open the browser and check whether the network is waiting for you to accept terms or sign in.