When your data allowance runs out, the line is almost never cut off. It slows down, or it costs money. At Orange Belgium and Telenet, you keep browsing at reduced speed until the next cycle; at DIGI Belgium, every extra GB is billed €0.60. And at Proximus, on some plans, the page does not say how much.
What happens when the data allowance runs out?
It depends on the contract, not on the phone.
On 14 October 2026 I recorded what each operator writes on its public pages and in its information sheets. Three regimes come out of it: reduced speed with no surcharge, billing per GB, and silence. The boxes I could not read stay "not published".
| Operator and plan | Included volume | After the allowance | Extra data |
|---|---|---|---|
| Orange Mobile Small | 12 GB | 512 kbps until the next cycle | 5 GB for €10, 15 GB for €20 |
| Telenet Mobile Basic | 15 GB | 1 Mbps until the next period | no top-up in the sheet |
| Telenet Mobile Unlimited | 300 GB | 1 Mbps | not applicable |
| Proximus Mobile Unlimited | 300 GB | 512 kbps, "no surcharge" | not applicable |
| Proximus Mobile Smart | 70 GB | not published on the page | not published |
| DIGI Belgium, 15 GB plan | 15 GB | billed per GB | €0.60 per GB |
| BASE, prepaid card | depends on top-up | out-of-bundle charged | Extra Data, price not published on the page |
Plan prices at the time of recording: Orange Mobile Small at €15 a month, commitment not published, list price recorded by this site on 12 October 2026; Telenet Mobile Basic at €21 and Mobile Unlimited at €41, undated information sheet, commitment and post-promotion price not published; Proximus Mobile Smart at €18.99 for twelve months then €24.99, and Mobile Unlimited at €34.99 then €49.99, both with no commitment according to the Proximus page; DIGI Belgium at €5 for 15 GB, commitment and post-promotion price not published.
The rule is federal. It is the same in Namur, Brussels and Ghent.
What is a 512 kbps connection still good for?
Staying reachable. Not watching a video.
The arithmetic is simple. A gigabyte is 8,000 megabits. At 512 kbps, it takes 15,625 seconds to get through, more than four hours and twenty minutes. At 1 Mbps, Telenet's reduced speed, just over two hours. Text messages, emails without heavy attachments, WhatsApp voice calls: they get through, with patience. A 300 MB app update takes close to an hour and twenty minutes.
At the shop counter in Namur, between 2013 and 2020, the customer who came back "because the internet doesn't work any more" had almost always used up his allowance on the 22nd of the month, on a billing cycle that restarted on the 1st.
How much does an extra GB of data cost?
Between €0 and €2 where the price is written down. Elsewhere, much more, or nothing displayed.
Orange Belgium sells two top-ups: 5 GB for €10, that is €2 per GB, and 15 GB for €20, that is €1.33 per GB. The amount is added to the bill. DIGI Belgium charges €0.60 per GB, or €0.0006 per MB according to its terms. Telenet, on its plan with no allowance, "Prijs volgens verbruik", charges €0.10 per MB: €100 per GB.
For Proximus, the figure is not on the plan's page. Test-Achats published on 1 July 2026 the case of a customer billed nearly €2,000 for about 15 GB used out of bundle, and recorded a rate of €0.12 per MB at this operator, that is €120 per GB. Proximus cancelled those charges for that customer. I have not read this rate in a dated Proximus document: I give it with its source, and I suggest you have it confirmed in writing.
For 5 GB over the allowance in a month, that gives €0 at Telenet (at 1 Mbps), €3 at DIGI Belgium, €10 at Orange Belgium if you want full speed back, and up to €600 at the rate recorded by Test-Achats at Proximus, unless a block is active.
Top-up or bigger plan: which costs less?
The bigger plan, from the second top-up. Often from the first.
At Orange Belgium, Mobile Small costs €15 a month for 12 GB, Mobile Medium €23 at list price for 70 GB (€16 for the first twelve months online, recorded on 12 October 2026). The gap is €8 a month for 58 GB more. A single 5 GB top-up costs €10. Someone who tops up once a month therefore pays €2 more every month for 53 GB less, that is €24 lost over a year and €48 over 24 months. At Proximus, moving from Mobile Smart to Mobile Maxi (140 GB, €21.99 for twelve months then €29.99, commitment not published on the page read) costs €5 a month at post-promotion prices.
Changing plan with the same operator does not, in principle, restart any term. The exception is a financed phone, covered in the article on changing your mobile plan mid-contract.
At Orange, a top-up expires after 40 days
And it expires even if you have not touched it.
The operator writes it on its page: the remaining volume "is deactivated after 40 days even if it has not been fully used". A 15 GB top-up bought on the 25th to finish the month expires early the following month, while your monthly allowance has come back in the meantime. DIGI Belgium, for its part, states that unused data is not carried over to the following month.
How do you block out-of-bundle usage?
By activating what the operator offers, before you go over. The tools recorded on 14 October 2026:
- Proximus, Full Control: a €0 option, activated in MyProximus, that blocks "all usage not included in your plan";
- Orange Belgium, National Data Control: you choose whether or not to block mobile internet once the allowance is reached, on the plans that allow it;
- Orange Belgium, alerts: a text at 80% of the allowance, then a second one when it is almost used up;
- every operator, the mechanism described by the BIPT: a text alert at the first overrun, then a second at €50 above the subscription by default, a threshold you can set at 0, 50, 75 or 100 euros.
That last point is often misunderstood. The alert warns you. It cuts nothing off.
Which step for which situation?
| Your situation | Risk | What to do |
|---|---|---|
| Allowance used up once a year | none, reduced speed | Wait for the next cycle, or a one-off top-up |
| Top-up bought every month | €24 a year lost at Orange | Move to the bigger plan |
| Plan whose page says nothing after the allowance | billing per MB | Ask for the rate in writing, activate the block |
| Proximus Mobile Smart or Maxi | out-of-bundle rate not stated on the page | Activate Full Control in MyProximus |
| Top-up bought at the end of the month | volume lost after 40 days | Buy as close as possible to the need |
| Disputed out-of-bundle data bill | high amount | Write to the operator, then to the Telecommunications Ombudsman Service |
To measure your real usage before choosing an allowance, the method is in the article on how many GB per month for your usage. Abroad, the rules change: see roaming in Switzerland and the UK.
Sources
- Orange Belgium, page "Ajoutez de la data à votre abonnement" (5 GB top-up at €10 and 15 GB at €20, 40-day validity) and help page "Comment éviter d'être hors forfait ?" (512 kbps, National Data Control, text alerts), consulted on 14 October 2026; legal notice for Orange Mobile Small, January 2026.
- Proximus, Mobile Smart and Mobile Unlimited plan pages: prices, twelve-month promotion, 512 kbps beyond 300 GB, Full Control option, consulted on 14 October 2026.
- Telenet, "Mobile residential" information sheet, undated: allowances, reduced speed of 1 Mbps, €0.10 per MB on the "Prijs volgens verbruik" plan, consulted on 14 October 2026.
- DIGI Belgium, mobile plans page: €0.60 per extra GB, no carry-over, consulted on 14 October 2026.
- BASE, help page "All about Extra Data" (prepaid card), consulted on 14 October 2026.
- Test-Achats, article of 1 July 2026 on a bill of nearly €2,000 for out-of-bundle data at Proximus, and table of out-of-bundle rates by operator.
- BIPT, alert mechanism for exceeding your usage (bill shock), consulted on 14 October 2026.
- Orange Mobile plan prices recorded by this site on 12 October 2026. Commitments and post-promotion prices not published by the operator have not been estimated.
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Fabrice D. a vendu des abonnements GSM pendant sept ans derrière le comptoir d’une boutique télécom à Namur, entre 2013 et 2020, puis a passé trois ans au service résiliations d’un opérateur virtuel belge — c’est-à-dire du côté où l’on lit les contrats à voix haute à des clients qui ne les avaient pas lus. Il sait donc exactement comment se construit un « GSM à 1 € » : un crédit de 24 mois posé à côté du forfait, avec son propre solde et ses propres conditions de sortie. Chaque mois, il relève les grilles tarifaires publiées par les opérateurs belges, note la date du relevé, et recalcule ce que chaque formule coûte au bout de deux ans, appareil compris. Ce qui l’agace dans son secteur : les prix d’appel affichés en gros pour douze mois, et l’écart — jamais imprimé nulle part — avec ce qui est facturé le treizième.