soda Journal
Is an unlimited eSIM really unlimited? Understanding FUP
“Unlimited” sounds like the safe choice, but here’s the detail most people miss. Nearly every “unlimited” travel eSIM has a fair usage policy (FUP) that throttles your speed after a certain amount. The “unlimited” part is really unlimited slow data.
This isn’t a scam, it’s industry standard. But you should know how it works before you buy.
What FUP actually is
A fair usage policy is the hidden line a carrier draws under an “unlimited” plan. The common shape: you get a high-speed allowance each day, a few GB say, and once you pass it your speed drops hard for the rest of the day, often slow enough that messaging works but video won’t. It resets the next day.
So “unlimited” usually means full speed for the first few GB, then a crawl.
Throttling comes in two flavours, and they feel very different
“Slowed down” actually splits into two kinds worth telling apart:
- A hard speed cap. Once you pass the allowance, your speed is locked to a low number, roughly like dropping back to 3G. It doesn’t matter whether the tower is busy; you’re just that slow.
- Lower priority. You stay as fast as everyone else until the tower you’re on gets congested (a crowded district, an event), and then the system puts you toward the back of the queue behind people who haven’t gone over. When nothing’s busy you barely notice; the moment it’s busy you slow right down.
So two plans can both say “throttled after X GB” while one means slow all the time and the other means slow only when it’s crowded. Carriers do this so a few heavy users can’t hog a whole tower, which is fair enough, but the effect on you is very different.
What that throttled speed can actually do
Plans love to write the throttled speed as “128 kbps,” “256 kbps,” or “1 Mbps,” which means nothing until you translate it. Roughly (illustrative, actual figures are set by each brand):
| Throttled speed | Still works | Already painful |
|---|---|---|
| 128 kbps | Plain text chat, basic email | Maps, Instagram, anything with images |
| 256 kbps | Small images in chat, text-only web pages | Video, and maps take ages to load |
| 512 kbps to 1 Mbps | Navigation usable, low-quality video that stutters now and then | HD streaming, uploading big files |
You don’t need to memorise numbers. The takeaway: anything under 256 kbps is genuinely miserable on a trip, while a floor around 1 Mbps is survivable. When you compare plans, that floor matters far more than the word “unlimited.”
How to read a plan’s FUP
When you look at an “unlimited” plan, don’t stop at the word “unlimited.” Look at two numbers: how much high-speed allowance you get (how many GB at full speed per day or per plan), and how slow it goes after that (can you still load a map, can you still message). Those two decide whether it’s actually usable, and they vary a lot between brands. That’s the real thing to compare.
Two real scenarios make it click
Scenario one: a five-day city trip, and you’re not a heavy user. You use maybe 1GB a day on maps, restaurant lookups, and sending photos. Plenty of “unlimited” plans set their high-speed line at 1 to 2GB a day, which means you never touch the throttle at all. In other words, the “unlimited” premium you paid for is something you never used. Buying unlimited here is paying for headroom you don’t reach.
Scenario two: you’ll binge shows on the train and hotspot for two friends all day. Hotspotting is the hungriest thing you can do. One hour of HD video can burn 1.5 to 2GB, and sharing your connection on top of that, you’ll likely blow past the daily high-speed line every day. Now unlimited earns its place, but pick one with a high threshold and a throttled floor near 1 Mbps, or your afternoons effectively go offline.
The difference between the two isn’t who’s a “better” user. It’s whether you actually hit the line. Most short-trip travellers are scenario one.
So is it worth it
Depends how you use data. If you stay under the daily high-speed threshold, the extra you paid for “unlimited” is wasted, because you never reach the unlimited part. If you’re a heavy user who blows past it daily, unlimited makes sense, but pick one with a high threshold and a usable throttled speed.
soda takes a different line. We don’t sell you an “unlimited” you can’t read; we bill by what you use and cap at the cheapest plan price. Use little and you pay little, use a lot and the cap protects you, and your balance never expires. Most people never reach unlimited territory anyway, so they keep what they’d have overpaid. The logic is in why you shouldn’t gamble on a plan, and sizing your own usage is in how much data do you need.
Common questions
After an unlimited eSIM throttles me, when does full speed come back? Most plans reset daily, so your high-speed allowance refills at midnight (in the plan’s time zone). A few share one high-speed total across the whole plan, meaning once it’s gone you crawl until the end. Check which kind you have.
Why is my unlimited plan still crawling at a concert or New Year’s countdown? That’s usually not a broken plan, it’s tens of thousands of phones hammering the same few towers. This “deprioritised when busy” effect hits unlimited users hardest, and no plan, however pricey, fixes it. See the concert section in the Korea eSIM guide.
Once I’ve used the high-speed allowance, can I top up to restore full speed? Some brands let you buy an extra high-speed pack; others make you wait until the next reset. Confirm before you buy. If you regularly need full speed, an unlimited plan that leans on throttling was the wrong pick anyway.
Unlimited or a clear “X GB per day,” which is the better deal? Depends on your usage. If you use less than X GB a day, a clearly labelled “X GB per day” is easier to read and usually cheaper; only genuine daily over-users need unlimited. The threshold is what matters, not the word “unlimited.”
Do unlimited eSIMs quietly auto-renew? Some do. Unlimited often comes bundled with a recurring plan that bills the next cycle automatically, and it’s easy to miss. To avoid bill shock, see overage and auto-renewal traps.
(FUP thresholds and throttle rules are set by each brand.)