Your US carrier says you have data abroad. So why won't anything load?

You land in Tel Aviv or Shanghai with a T-Mobile or Verizon plan that promises data in 200-odd countries. Your phone shows bars. And then Google Maps spins, WhatsApp photos never arrive, and you end up buying a local SIM at the airport anyway. This is not a fault. It is how the included roaming is designed. Here is what is actually happening, why paying for a data pass often doesn't fix it, and how to get real speed without giving up your US number.

What "included international data" actually means

Most US postpaid plans advertise data in a long list of countries. What they rarely put on the billboard is the speed of that data.

The included tier is deliberately capped — typically somewhere in the 128–256 kbps range depending on your plan and carrier. For scale, that is slower than a home DSL line from twenty years ago. It is genuinely enough for a text message and a very patient email. It is not enough for maps that re-route, a ride-hailing app, a boarding pass, a photo in a group chat, or anything with video in it.

So the plan is not lying to you. You do have data. You simply have it at a speed chosen to be useful for emergencies rather than for living.

Why the paid pass often doesn't rescue you either

Both major carriers sell an upgrade — a pass that buys back high-speed data for a set period or a set number of gigabytes. Sometimes it works well. Often people report that it doesn't, and there are two structural reasons why.

You are a guest on somebody else's network. Your carrier has no towers in Israel or China. It has a roaming agreement with a local operator, and you ride on their network as a visitor. Visiting traffic is commonly given lower priority than that operator's own paying customers. In a quiet village at 6am you may not notice. In central Tel Aviv at 7pm, or anywhere in a Chinese city, you will.

The pass has an end you can't see coming. It runs on a clock, a data cap, or both. When it runs out you are dropped back to the slow tier — usually without a helpful announcement — and the first you know about it is that your phone has stopped working properly again.

The result is a pass that costs real money and still leaves you unsure whether the problem is the network, your phone, or the app.

Two countries where we hear this constantly

Israel

Israel has excellent local mobile networks — travellers on a local plan get fast, reliable data almost everywhere. Visitors roaming on a US carrier frequently report the opposite: bars showing, nothing loading. The gap between what a local connection does and what a roaming connection does is unusually wide here, which is why so many people end up buying a local plan mid-trip after paying for roaming they can't use.

China

China has the speed problem and a second one on top of it. Many everyday services — the map you use, your email, your messaging app, the site you booked your hotel on — are simply unreachable from an ordinary local connection. So "fast data" alone doesn't solve the trip. What matters is how the connection routes your traffic. A traveller who buys the cheapest local data and finds their usual apps don't open has fixed the speed and not the problem.

The fix: split data from your phone number

The mistake is treating "my phone abroad" as one decision. It's two, and they are much easier apart:

• Data should come from a local connection, where you are a normal customer at full speed rather than a deprioritised guest.
• Your US number should stay exactly where it is, so the bank, the pharmacy, your family and your two-factor codes all still reach you.

A travel eSIM does the first without touching the second. It installs alongside your existing line — it does not replace it, and nothing about your US account changes.

1. Buy the data eSIM before you fly. Install it while you are still on Wi-Fi at home and your usual apps and email still work. Installing an eSIM needs an internet connection, and the worst moment to discover that is standing in an arrivals hall.
2. Set the travel eSIM as your data line. On iPhone: Settings → Cellular → Cellular Data, and pick it. Your phone will now use it for everything data.
3. Turn data roaming OFF on your US line — but leave the line itself on. This is the step people skip. The line stays active so it can still take calls and texts; turning its roaming off stops it quietly burning a paid pass or per-megabyte charges in the background while the travel eSIM does the actual work.
4. Turn on Wi-Fi calling for your US line, before you fly. Settings → Cellular → your US line → Wi-Fi Calling. Do it at home: some carriers only let the phone register the feature while you are still on their network, and a greyed-out toggle discovered abroad is a problem you cannot fix from there. From outside the US you also need a VPN set to a United States location, on before you make or take a call.

Does Wi-Fi calling need actual Wi-Fi?

Not strictly — and this is the part almost every guide gets wrong, in both directions.

Despite the name, Wi-Fi calling is not a Wi-Fi feature. It is your carrier's voice service delivered over an internet connection, and the phone does not fundamentally care which connection that is. On a dual-SIM phone your US line can carry its calls and texts over your travel eSIM's mobile data, with no Wi-Fi network anywhere in sight. When it happens on an iPhone you can see it: the status bar labels the US line "Using Cellular Data".

So people who tell you it strictly requires Wi-Fi are wrong. But people who tell you to rely on it are also wrong, because it is inconsistent, and it is worth knowing why.

Why it works for one traveller and not the next

• Your US line has to believe it has no service. This is the big one. If it finds a roaming partner and registers on it, it will use that connection and simply never fall back to the other line's data. One traveller described it exactly: their line "would still connect to the international cellular provider and would not switch over to Wi-Fi calling over cellular because it thought it had service." Turning data roaming off is not always enough — the line is still registered for voice. Switching the US line off and on again, once the travel eSIM has data, is what usually triggers the handover.
• Your carrier has to allow it. Wi-Fi calling while roaming is a carrier policy, not a phone setting. Some permit it freely, some only over genuine Wi-Fi, some not abroad at all. MVNOs — the smaller brands that rent capacity from the big networks — are the most likely to not support it.
• The feature has to be provisioned before you leave. If the Wi-Fi Calling toggle is greyed out, the carrier has not enabled it on your account. That is fixed with a phone call to them from home, and not fixable from a hotel in Tel Aviv.

The three ways this can go

Every traveller with a US line ends up in one of these. The difference is whether you chose it before you flew or discovered it on day one.

We cover more than 100 countries — see what is available for yours, with the validity clock starting on your first connection rather than at purchase.

If you don't have a US number at all

Everything above assumes you already have a US line worth keeping. If you don't — if you are moving to the US, studying there, or you need a US number for a bank, a marketplace or a verification code — that is a different product and we sell it separately: a real US carrier line, not a virtual number. US phone number plans start from the same page, and there is a fuller explanation in data eSIM vs US phone number.