When you see an eSIM plan with unlimited data, the fine print almost always hides a limit: the fair usage policy or FUP. This doesn't mean you're being misled, but it does mean that after a certain volume, your connection will no longer operate at maximum speed. In this guide, we'll tell you where that hidden cap is and how to choose a plan without unpleasant surprises mid-trip.
Do truly unlimited data plans exist?
Almost never. An eSIM plan labeled as unlimited typically offers full speed up to a daily threshold (e.g., 1 or 2 GB per day), and after that point, you can still browse but at a reduced speed. In other words: unlimited data in quantity, not in speed. That's the trap almost no one reads.
The reason is purely technical and commercial. The local operator providing coverage for the plan charges per gigabyte, so no provider can give away unrestricted traffic. Therefore, when a plan promises unlimited data without any conditions, it's wise to be suspicious and look for the fine print. An honest plan will tell you the exact threshold. If you want to delve deeper into the nuance, you'll find a complete analysis in our guide on whether unlimited data really exists on eSIMs.
What is FUP and how does it work?
FUP stands for Fair Use Policy. It's the clause that allows the provider to limit your speed when you exceed what's considered "normal" consumption. It doesn't cut off your service; it slows it down. FUP protects the network from a handful of users who would download terabytes and deplete capacity for everyone else.
Practical rule: if a plan says "unlimited" but doesn't mention any speed or threshold, the FUP still exists. It's just not as visible.
In practice, FUP is activated in two ways. The first is a daily high-speed cap: you consume 2 GB at full speed, and for the rest of the day, you're slower until it resets at midnight. The second is a total plan cap: 30 GB at maximum speed, and after that, reduced speed until the plan expires. Knowing which applies completely changes your daily experience abroad.
What speed reduction does each plan type have?
The reduced speed isn't the same across all plans, and that number makes the difference between being able to continue using your phone normally or being almost completely disconnected. Here's a realistic guide to what each tier offers after exceeding the FUP.
| Speed after FUP | What you can do | What suffers |
|---|---|---|
| 1 Mbps | WhatsApp, maps, email, text-based social media | High-quality video |
| 512 Kbps | Messaging, basic browsing | Streaming, fluid video calls |
| 256 Kbps | Only messaging and very light web browsing | Almost everything else |
| No reduction (cut-off) | Nothing until recharge | All connection |
A plan that reduces to 1 Mbps is still perfectly usable for the average traveler: maps, messaging, and browsing hardly notice the difference. The problem appears with reductions to 256 Kbps or, worse, with plans that cut off completely. That's why it's better to look at the reduced speed rather than the number of GB. If you're concerned about cost, knowing how much data you actually need for travel will help you avoid overpaying for an "unlimited" plan you won't maximize.
Real unlimited vs. fixed GB: when is each worth it?
The unlimited plan doesn't always win. If your consumption is moderate—checking your phone, maps, an occasional video—a fixed GB plan is usually cheaper and offers full speed all the time. Unlimited with FUP is worthwhile when you spend many hours connected, share data via hotspot, or don't want to keep track of your usage.
- Short trip and light use: fixed GB is better (3-5 GB is usually more than enough for a week).
- Nomad or remote worker: unlimited with high FUP, so you don't run out.
- Sharing with partner or family: unlimited, because consumption skyrockets when using hotspot and sharing the connection.
The key is that an honest fixed GB plan is more transparent than an unlimited plan with fine print: you know exactly what you're buying. At PuraSim, you can choose between GB-based or daily plans according to your route, with activation in 1 minute and 24/7 Spanish-speaking support.
How to detect the limit before buying
Before paying, take two minutes to read the plan details. These are the pieces of information you absolutely must find, because they reveal the real limit hidden behind the word "unlimited."
- High-speed threshold: how many GB per day or in total will be at maximum speed?
- Reduced speed: how many Mbps or Kbps does it drop to after exceeding the FUP?
- Scope: does unlimited apply in all countries covered by the plan or only in some?
- Reset: does the daily cap reset every day or is it a one-time allowance?
If the plan details don't answer these four questions, ask support before buying. A good provider will tell you straightforwardly. And be careful with comparisons: many comparison sites only show the price and "unlimited GB," hiding the reduced speed. To avoid this, check our guide to the best cheap eSIM of 2026, where we compare plans with the fine print included.
Tips to avoid connection throttling
Even if your plan has FUP, you can extend your full speed if you manage your consumption well. Most people exhaust their daily threshold due to automatic downloads they don't even notice, not through their conscious mobile usage.
Tip: disable background app updates and automatic video playback on social media. That alone will significantly reduce invisible consumption.
Other effective measures include downloading maps and playlists via Wi-Fi before leaving the hotel, lowering streaming quality to standard, and limiting cloud backups to Wi-Fi networks. With these habits, many travelers don't even hit the FUP threshold all day. If you want to get even more out of your plan, you'll find a complete list of tips to save data abroad that apply to any eSIM.
Frequently asked questions
Is unlimited eSIM data truly unlimited?
In quantity, almost always yes: you won't run out of data. In speed, no: upon exceeding the fair usage policy (FUP) threshold, the connection speed will drop. That's why we talk about a hidden limit, not a trick.
What happens when I reach the FUP limit?
You can still browse, but at a slower speed. Depending on the plan, the speed drops to 1 Mbps, 512 Kbps, or less. At 1 Mbps, you can still use maps, messaging, and email normally; at lower speeds, you'll notice slowness in video and video calls.
Does the cap reset daily?
It depends on the plan. Many unlimited plans have a daily high-speed cap that resets at midnight, so you'll have full speed again each morning. Others apply a total cap for the entire duration of the plan. Check the plan details before buying.
Is an unlimited plan or a fixed GB plan better?
If your usage is moderate, a fixed GB plan is usually cheaper and offers full speed all the time. Unlimited plans are worthwhile if you spend many hours connected, share data via hotspot, or don't want to keep track of your usage.
How do I know the reduced speed before buying?
Look for it in the plan details, usually next to the data threshold. If it's not there, ask support. A transparent provider will tell you both the GB at maximum speed and the speed it reduces to after the FUP.
Conclusion
Unlimited data exists, but with nuances: FUP marks the point at which your speed drops. What's important isn't the number of GB, but at what speed you can browse afterward. Choose a plan that clearly states its fine print and match the plan type to your actual consumption. At PuraSim, you have clear GB-based or daily plans for 218 destinations, with activation in 1 minute. Explore all plans and travel without surprises.
