"Without you noticing the change": what your company's official guide says about roaming

There's a phrase, written by a telecommunications company about its own service, that explains more about international roaming than any price comparison.

It's in a public document. You don't have to ask for it or look for it in any register. It's been on their website for years, in the section for customers traveling abroad.

And it says, describing a very specific situation, that charges can be incurred without you noticing the change.

What situation exactly does it describe?

The paragraph refers to an everyday scenario: having Wi-Fi active, and at the same time, having data roaming active.

When that happens and the Wi-Fi signal is lost, the phone doesn't disconnect. It automatically switches to the mobile network of the country you're in and continues browsing. This usage is billed at the international rate.

Source: International Traveler's Guide, official document published by Telcel on its website.

It's worth dwelling on what this implies, because it's not a rare case. It's the most common case of all.

Someone abroad enters and leaves Wi-Fi networks dozens of times a day: the hotel, breakfast, the museum, the mall, the airport, the restaurant. And they keep walking while the phone works in the background syncing email, backing up photos, and updating apps.

In each of those gaps, if the second switch is active, consumption continues.

Two switches that almost everyone confuses

This is the technical root of the matter and explains why it happens even to careful people.

In any phone's settings, there are two distinct settings with similar names:

• Mobile data controls whether the device uses internet from the cellular network.
• Data roaming, or roaming, controls whether the device can connect to operator networks in other countries.

Turning off the first and leaving the second on leaves open exactly the door that the guide describes. And the second can remain active due to a system update, a device change, or simply because it was never touched.

It's not a silly oversight. These are two different menus with two similar names, and no screen warns of the difference when it matters.

It's worth adding something else. Even if both switches are correctly turned off, some users are still exposed: those who share the device with someone less familiar with the settings, and those who travel with elderly people whose phone backs up photos and syncs email without them touching anything. The person who uses the cell phone the least can end up being the one who consumes the most, precisely because the device works on its own.

That's why the solution of relying on a manual adjustment works poorly as a family strategy. Asking four different people, two of them in their seventies, to be careful is not a plan.

What makes the Mexican case different

Here's a piece of information that changes the perspective of the whole matter.

Since 2017, the European Union has banned roaming surcharges between its member countries. A resident of Spain crossing into France or Italy continues to use their phone with their usual plan, with no additional charges.

It's not a different technology. It's the same antennas, the same equipment, and the same operators. The difference is regulatory, not technical.

In other words: charging differently is perfectly possible and works for hundreds of millions of people every day.

From Mexico, this doesn't exist. Here, international roaming is always paid for, and that's why the problem is universal for anyone leaving the country, with no exceptions or special cases to memorize.

The second variable no one checks: the destination zone

Mexican operators do not apply a single international rate. They apply zones, and the difference between them is of another order of magnitude.

The published catalog includes a 15 GB package valid for 20 days for the United States, Canada, Latin America, and Europe, and a Rest of the World zone package of 20 MB for 6,000 pesos. For maritime navigation, there is a 1 MB package for 400 pesos.

Source: International roaming rates published by Telcel and registered in the Tariff Book with the Federal Institute of Telecommunications.

Twenty megabytes is less than what a photo taken with a modern phone occupies.

This table decides how much the trip will cost in terms of data, it's published, and practically no one consults it before buying a ticket. The agency doesn't mention it, it doesn't appear when buying the flight, and no one reads it when contracting a plan.

The case of packages described as unlimited

There is a third source of surprises: intentionally purchasing a travel package and still being left without useful service halfway through the week, because behind that word there is always a fair use policy with a published threshold.

AT&T Mexico publishes roaming packages with their price and conditions on its website. Their Preferred 5-day package costs 299 pesos and includes 2,500 MB, and upon exceeding that amount, the speed is reduced to 256 kbps. The 10 and 17-day packages follow the same logic with 5,000 MB and 8,500 MB.

Source: att.com.mx, international plans and roaming section.

At 256 kbps, a text message can be received. A map with real-time traffic or a menu code will not load.

Here it's worth being honest the other way around too: no company in the world offers data without any limit. All of them have a fair use policy with a threshold at which they reduce speed. The difference between them is not whether the limit exists, but whether it appears next to the price or three screens deeper.

Why the problem isn't the price, it's the timing

When these three things come together, a pattern emerges that explains more than any rate.

A trip is almost entirely organized from home. Flight compared and bought months in advance. Hotel booked after reading reviews. Insurance purchased. Tickets bought online. Currency exchanged here. Suitcase weighed before leaving.

And there's one thing that almost everyone leaves pending, precisely the thing they're going to use every hour of every day.

That decision ends up being made after a long flight, with luggage, tired, often at night and in another language. At that moment, no one compares anything. They accept what's available.

The mistake, seen this way, is not having chosen the wrong package. It's having left the choice for a moment when there was no longer any possible choice.

What can be set up from home

Today, there is an alternative to buying data in advance, from Mexico, for the destination country, without a physical SIM card.

Digital profiles, called eSIMs, are a file that is downloaded to the phone using home Wi-Fi. This has three direct consequences on all of the above:

1. The price is fixed and prepaid. If there is no open consumption, there is nothing that can appear on the bill weeks later. The problem addressed in this text disappears entirely.
2. You don't have to remove the Mexican SIM card. It stays in the phone, so the number, WhatsApp with all its groups, and bank messages remain the same. The only thing that changes is how data goes out.
3. There's nothing to do upon arrival. No counter, no line, no passport, no hourly registration.

And there's a fourth point that makes all this viable in advance: in the case of PuraSIM, the plan days run from the first use at the destination, not from the purchase, and there are 180 days to install it. That's why you can buy it today, install and check it this week, and travel in two months without losing a single day.

Before paying, a ten-second check

It's advisable to check that the device supports digital profiles, and this is done on the phone itself without installing anything.

Open the dial pad and type `*#06#`. A screen will appear with the IMEI and, if the device is compatible, also a number called EID.

Two specific warnings for Mexico: several Redmi and Xiaomi models sold here are the Latin American version and do not include the component even if the international specifications say otherwise; and being unlocked is not the same as being compatible.

What to remember

• The unexpected charge almost never comes from misuse, but from open consumption without a cap while abroad.
• Telcel's official guide describes in writing a scenario where such consumption occurs without the user perceiving it.
• Turning off mobile data is not the same as turning off data roaming.
• Since 2017, the European Union has banned these surcharges between its countries, which shows that the limitation was never technical.
• Rates change radically depending on the destination zone, and that table is published but almost no one consults it.
• All of this can be set up from home, with a fixed price, before getting on the plane.

PuraSIM sells destination-specific data plans that are purchased and installed from Mexico before traveling, with a fixed price, for more than 200 destinations. Customer service is via email and WhatsApp, with people who respond in Spanish. There is no phone support.