Not all countries cost the same: the zone table that determines your roaming bill

There is a very widespread and very reasonable belief: that a megabyte of data costs roughly the same everywhere, like electricity or water.

It is false. And the difference is not ten or twenty percent. It is an entirely different order of magnitude.

What determines how much a trip's internet will cost is not how much you use your phone. It is which zone the destination country falls into according to your carrier's table. That table is published, you can look it up, and almost nobody checks it before buying a plane ticket.

How the zone system works

Mexican carriers group the world's countries into categories. The names vary by company, but the logic is the same.

There is a large, predictable group where rates are reasonable: the United States, Canada, much of Western Europe, and much of Latin America. These are the destinations with the most traffic and where the carrier has the best wholesale agreements.

And then there is everything else. This includes destinations that are not exotic at all for the Mexican traveler: parts of Asia, Africa, the Middle East, some Caribbean islands, and several Eastern European countries. For the user, they are a normal tourist destination. For the table, they are another category.

The underlying reason is that roaming was born as an agreement between carriers, not as a service designed for the customer. The price is set between companies that charge each other and pass the bill on to the person traveling. That is why the numbers are so hard to explain in terms of real cost.

The published numbers

In Telcel's international roaming catalog, products that look nothing alike coexist:

• A 15 GB package valid for 20 days for the United States, Canada, Latin America, and Europe, for 949 pesos.
• A package from the Preferred Countries B category with 100 MB valid for 30 days, for 1,949 pesos.
• A package from the Rest of the World category with 20 MB valid for 30 days, for 6,000 pesos.
• For maritime navigation, a 1 MB package for 400 pesos.

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

It's worth translating that last figure, because on its own it means nothing. Twenty megabytes is less than a single photo taken with a modern phone. It's what a device sitting idle in a bag can use while syncing email and checking for updates.

The special case of cruises

This deserves a separate mention because it catches even experienced travelers off guard.

When the ship is at sea, your phone doesn't connect to a land-based antenna. It connects to the ship's own satellite antenna, and that connection is billed differently and significantly more expensive than normal terrestrial roaming.

Many people assume that at sea there's simply no signal. There is, and your device will connect to it if data roaming is on. This is one of the scenarios where the most unintentional data usage happens, because the passenger is convinced they're offline.

Why nobody tells you

This is the part that annoys people the most when they go through it, and the explanation is pretty straightforward.

The table is published, but it never shows up at any of the moments when it would actually be useful. The travel agency doesn't mention it when selling a package. It doesn't appear during the flight booking process. It doesn't come up when booking a hotel. And if you call your carrier to ask about something else, nobody reads it out to you.

It lives in a section of the carrier's website that you only reach if you already know it exists and go looking for it.

The practical result is that most people discover their destination's zone when they check the breakdown of a bill — in other words, after the usage has already happened and there's nothing to be done about it.

How to check before you buy your ticket

This is the most useful tip in the whole article and it costs nothing.

Before you book a trip to a destination that isn't the US, Canada, Western Europe, or Latin America, it's worth spending ten minutes doing the following:

1. Go to your carrier's website and find the roaming or international travel section.
2. Look for the list of countries by zone and find your specific destination.
3. Check what packages are available for that zone, including the data amount and price.
4. Add that number to your trip budget, right alongside the flight and hotel.

If your destination falls in an expensive zone, that single check changes your entire planning. And if it falls in a good zone, you can travel worry-free knowing why.

The mistake of calculating by days instead of by zone

There's a very common way of thinking that leads to wrong decisions, and it's worth pointing out because it's counterintuitive.

Many people estimate their data costs for a trip based on how long it lasts. Ten days costs more than four, twenty more than ten. It seems logical.

In practice, the biggest factor isn't duration but zone. A short trip to an expensive-zone destination can cost much more in data than a long trip to a destination on the good list, even if the second trip lasts three times as long.

That leads to a simple rule that works for planning: the first question isn't how many days you're going, but where you're going. And that question is answered by checking the table, not by calculating.

There's a second related mistake. When someone travels to an unusual destination, they usually research visas, vaccines, safety, and transportation thoroughly, but almost nothing about connectivity. Yet connectivity is exactly the variable that changes most in those destinations, precisely because they fall outside the preferred zones.

The alternative that doesn't depend on your carrier's zone

There's another path, and its main advantage is precisely that it ignores that table.

Destination data plans bought from Mexico before you travel don't go through your carrier's toll. You contract direct access to local networks in the country you're visiting, with a fixed price paid in advance.

That has three concrete effects on the problem this article describes:

1. The price is known upfront and doesn't depend on which category the country ended up in on someone else's table.
2. There's no open usage, so nothing can show up on your bill weeks later.
3. The destinations that fall in your carrier's most expensive zones are exactly where the difference is most noticeable.

You no longer need a plastic SIM card: they're digital profiles, a file you download to your phone from home. Your Mexican SIM card stays in, so your number, WhatsApp with all its groups, and your bank messages all keep working as usual. The only thing that changes is where your data goes through.

With PuraSIM, there's coverage in over 200 destinations, your plan days start from first use and not from purchase, and you have 180 days to install it. That's why you can buy it today, install and test it at home, and travel two months later without losing a single day.

Frequently asked questions

What if I travel to several countries on the same trip?

It's worth checking each destination before you buy, because some plans cover multiple countries in the same region and others don't. That's exactly the kind of detail you sort out at home, not on a train platform.

Do I still need to pay for my Mexican plan?

Yes, your Mexican line is still your own and you pay for it as usual. What you're buying is an additional data plan just for the duration of your trip.

Does it work for local phone calls?

Data plans don't include a local number. Calls are made through messaging apps. It's good to know this beforehand if your trip involves any procedures that require a local phone number.

How do I check if my phone is compatible?

Open the dialer keypad and type `*#06#`. If an EID number appears alongside the IMEI, the device supports digital profiles. Two warnings for Mexico: several Redmi and Xiaomi models sold here are the Latin American version and don't include it even if the international spec sheet says otherwise, and being unlocked is not the same as being compatible.

What to keep in mind

• Mexican carriers apply zones, not a single international rate.
• The difference between zones isn't a percentage — it can change the order of magnitude of the cost.
• The rate table is published, but it never shows up at any of the moments when you'd actually need to see it.
• Cruises have their own rates because the phone connects to the ship's antenna.
• Checking your destination's zone before you buy your ticket takes ten minutes and avoids the whole problem.

PuraSIM sells data plans by destination that you buy and install from Mexico before you travel, with a fixed price, for over 200 destinations. Customer support is by email and WhatsApp, with people who respond in English. There is no phone support.