Test-Aankoop did the maths: switching easily saves you €100 a year (and UNDO ranks among the best-value picks)

Your mobile plan is one of those bills you pay without looking at it anymore. Until someone else does the maths for you.

At the end of June, Belgian consumer organisation Test-Aankoop published a new comparison of mobile plans in Belgium. The conclusion is clear: switching to the best-value plan for your actual usage quickly saves you close to €100 a year. And for people who mostly call and browse moderately, UNDO — alongside a few other challengers — comes out among the best-value choices: on average over €36 cheaper per year. The three big operators? They don’t make the top 10 for that usage profile.

That’s not us saying it — it’s the independent consumer organisation. And that’s exactly why we’re happy to share it here: you don’t have to take our word for it.

Compare for yourself via the Test-Aankoop tariff comparator or via the official BIPT comparator (besttariff.be).

Why comparing pays off right now

The first half of 2026 was anything but quiet on the Belgian telecom market. Several operators raised their prices — sometimes even mid-contract. Good to know: in most cases such a price increase opens the right to cancel free of charge, provided you react in time. The moment your bill goes up is also the moment switching is easiest.

And switching itself? It’s no longer a hassle:

• Your number moves with you — your new operator handles the transfer; you don’t even have to cancel your old plan yourself.
• No fixed contract — at UNDO you’re not tied to anything; you can leave any month (though we obviously hope you won’t).
• With an eSIM you’re up and running in minutes — no SIM card in the post, no shop visit.

The saving nobody counts: your unused data

A price comparison looks at what you pay. But there’s a second kind of waste that rarely shows up in the tables: what you pay for and don’t use.

At most operators, the gigabytes, minutes and texts you didn’t use simply evaporate every month. Paid for, unused, gone. At UNDO it works differently: whatever you don’t use this month simply rolls over to the next. Your data stays your data. That way you build up a buffer for busier months — a holiday, a month without wifi — without having to take a bigger bundle “just in case”.

No small print, no credit that expires: just your own, real unused bundle that stays put.

Check for yourself in 5 minutes

1. Look at your latest bill to see how many GB, minutes and texts you actually use.
2. Compare via an independent comparator (Test-Aankoop or the BIPT tool) based on that usage — not on the bundle you picked years ago.
3. Got a price increase? Check whether you’re entitled to cancel for free.
4. Switching? Keep your number, done.

At UNDO that starts from €4 a month — and every activation contributes to our reforestation projects in Congo and Belgium. But start with the comparison, not with us: the numbers speak for themselves.

Source: Test-Aankoop, comparison of the cheapest mobile plans, June 2026. Amounts and ranking as published by Test-Aankoop at the time of writing; tariffs may change.