Marco had a great few days in Switzerland. Lucerne in the morning, a train along the lake, a work call squeezed in from a café in Zurich before dinner. The call ran long — video on, screen shared, the usual. He didn't think twice about it. He was on holiday; the phone just worked.
The bill thought about it for him. Back home the following week, his statement showed almost €100 in roaming charges — nearly all of it from that one video call. No warning, no cap, no obvious mistake. Just a phone quietly doing the most expensive possible thing.
It's one of the most common connectivity traps in Europe, and it catches careful people. Here's exactly how Marco's €100 happened — and the two-minute setup that makes it impossible.
Why Switzerland is a roaming landmine
If your SIM is from an EU or EEA country, the "roam like at home" rules let you use your domestic data across the bloc at no extra cost. It's easy to assume Switzerland is part of that deal. It isn't.
Switzerland is not in the EU, so those price caps simply don't apply. Roaming there falls back to whatever your operator charges out-of-network — historically some of the highest rates on the continent. Worse, the border regions are sneaky: near Lake Geneva or the Italian frontier, your phone can silently latch onto a Swiss tower even when you think you're "in the EU". One roamed session on that network and the meter is running at Swiss rates.
A short video call is the perfect storm. Video is data-hungry, and on a home line abroad that data is billed by the megabyte with no ceiling. Marco wasn't reckless — he just didn't realise the call was riding the one connection that had no protection.
The part that really stings: your phone used the wrong line
Here's the detail almost nobody checks, and it's the whole ballgame: make sure your data is actually going through your travel data line, not your normal mobile number.
Modern phones are dual-SIM. You can have a data eSIM installed and still route everything through your primary SIM — because installing an eSIM doesn't automatically make it the line your phone uses. If your primary SIM has data roaming switched on, the phone will happily use it, at full roaming price, while your cheap travel plan sits there untouched.
That's how people end up paying twice: they buy a travel eSIM, feel protected, and never flip the two settings that make it do its job. The eSIM is only insurance if it's the line actually carrying your data.
How a VamosData eSIM keeps the bill flat
A VamosData eSIM turns "however much my operator feels like charging" into a fixed, known price you pay up front. You install it before you fly, it carries your data at that flat rate, and there's no per-minute meter waiting to ambush you three towns from a border.
The practical wins:
- A price you already agreed to. No uncapped out-of-network rate, no midnight-renewing "roaming pass".
- Your own number stays reachable. Keep your home SIM in the phone for calls and texts — with its data roaming off — and let the eSIM handle the internet.
- One setup for the whole trip. Crossing into non-EU stops like Switzerland (or the UK) doesn't break anything, because you were never relying on EU rules in the first place.
If you're weighing this against a local shop SIM or your carrier's daily pass, our eSIM vs physical SIM guide lays out the trade-offs, and how to avoid roaming charges in Europe covers the wider map of traps.
The two-minute check before your first call
Do this once, on the plane or at the gate, and Marco's bill can't happen to you:
- Install your travel eSIM before departure — set it up on Wi-Fi at home while it's easy. Not sure your phone supports one? Our device checker answers in seconds.
- Set the eSIM as your data line. In your phone's cellular settings, choose the eSIM for "mobile data". iPhone and Android both make this a single toggle — the steps are in our iOS and Android guides.
- Turn data roaming OFF on your primary SIM. This is the one that saves you. Your home number still rings and texts; it just can't rack up data charges in the background.
- Make calls over data. A video or voice call through a messaging app runs on your flat-rate eSIM data — not the metered home line.
That's the entire fix. Two settings and a habit.
Browse plans for your route on our destinations page, install before you leave, flip those toggles — and the only thing your trip to Switzerland brings home is the photos.