Paris sends two very different long-haul evenings across the Atlantic, but the phone setup can be the same. Check the French contract for service outside Europe, buy the Latin America eSIM, and install it on dependable home Wi-Fi before boarding. Mexico and Brazil are both in its exact destination list, so one profile and one shared allowance can cover the two-country route. Installation does not spend the purchased validity; its first successful connection in Mexico or Brazil starts the period. Hotspot sharing is free on every Horizon plan, and connected devices use that same allowance.
Where the European rules stop
Inside Europe a French line mostly forgets it has left home, and a couple of holidays in Spain or Portugal are enough for its owner to forget too. The forgetting is the part that costs money. Those rules have an edge, Mexico and Brazil lie well past it, and past it the terms governing your line come out of your own contract and nowhere else.
Ten minutes with that contract, a week out, is the whole job. Look for the clause covering the rest of the world, then read what it sets out for data, for voice, and for the background traffic a handset produces on its own. Most people finish reading and land on the same split: the French line keeps the number, and travel data comes from something bought for the country in question.
Before the gate, not at it
Pay and install several days ahead, sitting down. Long-haul days out of France rarely start at the gate — a TGV into Roissy, an early hop up from Lyon, Marseille or Nice, the transfer between Orly and Charles de Gaulle — so by boarding you have been awake and moving for a long time. Terminal Wi-Fi will open a message; it is a bad place to attempt a first profile download.
Three jobs belong to the kitchen table. Keep the order confirmation and installation code somewhere other than the receiving phone. Save the first address and pickup in each country in a note that opens offline. Installation leaves purchased validity unused. Horizon counts the period from the profile’s first successful connection in an included destination, so preparing it in France does not spend travel days.
Landing in Mexico
With the profile already installed, arrival is a settings job rather than another activation step. After landing in Mexico, select Horizon for mobile data and enable data roaming on that line. Its first successful local connection starts the validity you bought; there is no reason to wait until after immigration if you need airport messages.
Keep the French line available for its number if your phone supports two SIMs, but disable automatic cellular-data switching. Calls or texts handled by the French operator can still carry its roaming charges. The travel profile supplies data only, including WhatsApp and other internet calls.
Then the geography takes over. At Benito Juárez the pickup arrangements differ between the two terminals, and the link running between them is not the transfer into the city. Cancún separates into three pins as well — where you land, the hotel strip, and the address itself — and the meeting point normally sits in the last message a driver sent rather than in the booking.
Landing in Brazil
Brazil rearranges the same three questions. Rio's international traffic arrives at Galeão, a good twenty kilometres from Copacabana; Santos Dumont, two kilometres or so from the centre, is where most domestic legs leave from, which means a Rio stay can quietly include a change of airport. São Paulo's long-haul flights land at Guarulhos, well out of town, and the road in is a stage of the journey, not a detail at the end of it.
Then you start typing. A driver at the kerb will describe in Portuguese which side of the building he has pulled up on and expect a reply within the minute. Whichever messaging application you already use is the one carrying that exchange, so sign into it and test it in France.
What the two trips demand
Mexico charges the phone for movement. Its regions are joined by flights rather than roads, so a two-region itinerary arrives twice, and the stretch of coast below Cancún is a relay of separate bookings — a car, a bus or train leg, a boat, one final collection — each with its own company and its own written arrangement. Sit on one beach for a week and almost none of that applies, until the weather rewrites an afternoon.
Brazil charges it for distance. Salvador lies some 1,650 kilometres up the coast, Foz do Iguaçu roughly 1,100 inland, and neither is a drive; the six-hour bus along the 430-kilometre corridor to São Paulo is the exception people actually take. Rio's days go upward as well as along: the climb up Corcovado and the ride to the top of Sugarloaf both put you above the city rather than in it, and their ticket times are better read early.
Two countries, one regional profile
Mexico and Brazil are both included in Horizon’s Latin America eSIM, alongside Argentina, Chile, Colombia, Costa Rica, Ecuador, Peru, El Salvador and Uruguay. One purchased profile carries a shared allowance across those ten destinations where service is available. Bolivia, Paraguay, Belize, Guatemala, Honduras, Nicaragua and Panama are outside that exact list. Compare the regional option with country-only plans before buying; do not treat the name as coverage for every country on the map.
Sizing belongs to the two longer guides. Choosing well in Mexico turns on the gap between the Yucatán and the high interior; the Brazilian version turns on a language most visitors read better than they speak. Compressed to a line: a normal fortnight in either country points at something near ten gigabytes, and the day count deserves more thought than the allowance does, since a window that runs out before the return flight is the expensive kind of mistake.
Current allowances and validity sit on the Mexico eSIM, Brazil eSIM and Latin America eSIM pages. If the itinerary contains both countries, compare the one regional checkout total against the two country-only totals. If it stays in one, compare only the options that fit that country and the full trip dates.
Keeping the French number
Data is all the travel profile does, and that is deliberate. The number you have always used stays on the line it came in on, still ringing, still taking text messages, still taking whatever code a French bank sends when a card appears abroad. What those calls and texts cost outside Europe is, once again, a question for your contract.
Tip: A French card used at a counter in Guadalajara or a kiosk in Salvador often triggers a confirmation step, and the bank sends it to the number on its file. Install the bank's own application and confirm that the number on file is the French one still in the phone. A card reader that has already refused you is a poor place to find out.
A Mexican or Brazilian number is a different product, and the regional travel profile remains data-only. WhatsApp and other internet calling apps use its shared allowance, but ordinary calls and SMS stay with the French line and may attract that operator’s roaming charges. On the way home, return mobile data to the French line; the Latin America profile can remain installed on the phone.
Short answers
Does my French contract work in Mexico and Brazil? On whatever terms it sets for the rest of the world. Nothing else answers it, so look before you book.
How long are the flights? About eleven to twelve hours nonstop to Mexico City or São Paulo, and not far off that for Cancún or Rio de Janeiro.
Can one plan cover both countries? Yes. Horizon’s Latin America plan lists Mexico and Brazil, so the same regional profile can serve both on one shared allowance.
When does that profile start? Installing it in France does not start the purchased validity. Its first successful connection in Mexico or Brazil begins the period; select Horizon for data after landing.
Do I keep my French number? Yes. It stays on its own line, the bank codes still reach it, and only the data moves.
