By Lisa Salter
Montreal travel advisor · Updated June 26, 2026
You've heard an eSIM is "a digital SIM" — but how does it actually work, and how does it get you online in another country? Here's the plain-English explanation, no tech background needed.
Ready to put one to work on your next trip?
See eSIM plansThe mechanism, in plain terms
Every recent phone has an embedded SIM chip built inside — that's the "e" in eSIM. A physical SIM stores your carrier details on a removable card; an eSIM stores the same kind of details as a downloadable profile on that built-in chip. Buying an eSIM simply downloads a new profile (via a QR code or app), and your phone can hold several profiles at once and switch between them in Settings — no card, no swapping.
How it connects you abroad
A travel eSIM provider has agreements with mobile networks around the world. When you arrive and switch your eSIM on, its profile authenticates with a local partner network — say a carrier in Mexico or Japan — and you get data at local rates instead of your home carrier's roaming prices. Because it's using a partner network, the eSIM line needs "Data Roaming" turned on to connect — that's normal and free, since it's the eSIM's own data, not your Canadian carrier's roaming.
Dual-SIM: how your number and the eSIM coexist
Modern phones are dual-SIM — they run two lines at once. You keep your Canadian line as your primary number for calls and texts, and set the eSIM as your data line for the trip. Your phone uses each line for what you've assigned, so you stay reachable on your own number while the eSIM quietly handles the internet.
One phone, several eSIMs
You can store multiple eSIM profiles and switch between them — handy if you travel often. Finished with a trip? Turn that eSIM line off or delete the profile; it won't charge you, and the slot is free for next time.
How it works for your trip
In practice it's three steps: buy a plan, install it on Wi-Fi at home, and switch it on when you land. We cover the full routine in how to use an eSIM for travel, and the exact iPhone steps in how to activate an eSIM on iPhone. New to the whole idea? Start with what is an eSIM.
Frequently asked questions
Does an eSIM need a physical chip?
The chip is already built into your phone. You don't insert anything — you just download a carrier profile onto the chip that's already there.
How does the eSIM know which network to use?
The downloaded profile contains the carrier details. Abroad, a travel eSIM's profile is set up to connect to a local partner network automatically.
Can I have more than one eSIM on my phone?
Yes. You can store several profiles and switch between them in Settings — only one or two are active at a time, but they're all saved.
Does an eSIM work without my home carrier?
Yes. A travel eSIM is independent of Rogers, Bell or Telus. It connects through its own partner networks; your home plan isn't involved.
Why does the eSIM need Data Roaming switched on?
Because it connects through local partner networks, which technically counts as "roaming" on that line. It's free — it's the eSIM's own data — and it's what lets the eSIM connect abroad.
Don't want to learn the mechanics? You don't have to. Lisa Salter, a Montréal travel advisor, picks the right eSIM for your trip and sets it up with you — in French or English — so it just works when you land. Ask Lisa →
