Yes, for almost every sale. A card machine has to ask the customer's bank for an authorisation before the payment is approved. That request needs a connection, whether that is fixed broadband, the shop's wifi, or a SIM inside the terminal.
There is a narrow exception. Chip cards support offline authorisation, where the terminal approves a small payment on its own and sends the record later. It is real, it is limited, and most merchants never switch it on.
Every shopkeeper has had the day when the line drops and the queue is still there. The terminal is charged, the chip is readable, the customer is willing, and nothing happens. Understanding why is worth a few minutes, because the answer decides what you can do about it.
How a card payment gets approved
- The card is read
Chip, contactless or magnetic stripe. The terminal gets the card number, the issuer and the security data the card is prepared to give it.
- The terminal builds a request
Amount, currency, merchant identity, card data and a set of risk checks, packaged into an authorisation request.
- It goes to the acquirer
The merchant's payment provider receives the request and routes it through the card scheme to the bank that issued the card.
- The issuer answers
Funds, limits and fraud rules are checked, and an approval or decline comes back. This is the step that fails when the connection fails.
- Settlement happens later
Approved transactions are batched and settled afterwards, which is why the money reaches the merchant days after the customer sees it leave.
What a terminal can decide on its own
Chip cards were designed in an era when connections were expensive and unreliable, so the standard allows the terminal to approve some transactions without asking anyone. Three things make it possible.
Offline data authentication. The chip carries cryptographic data the terminal can verify locally to satisfy itself that the card is genuine and not a clone.
Floor limits. The acquirer sets a value below which a terminal may approve without going online. Above it, an online authorisation is mandatory.
Store and forward. The terminal holds approved transactions and uploads them once the connection is restored, normally within a set window.
What the terminal cannot do is see the balance. It does not know whether the money is there. It is making a risk judgement, not a verification.
Offline approval is not the terminal knowing the money is there. It is the merchant betting that it is.MobiBank Editorial
The risk lands on the merchant
If an offline approved transaction is later rejected because the account was empty, the card was blocked or the card was fraudulent, the merchant is usually the one who absorbs it. There is no authorisation code to point at.
That is why most terminals are configured to require an online authorisation on every sale, why contactless above the local limit always goes online, and why staff are told to decline rather than improvise when the line is down. It is a deliberate choice, not a technical shortcoming.
What the terminal is actually using
Most card machines have more than one route out and will fall back between them. Fixed broadband or a router in the shop. The shop wifi. A SIM card in the terminal, which is why a portable machine keeps working in a restaurant garden. Some pair to a phone and borrow its connection.
This redundancy is why single failures rarely stop payments. It is also why a regional power cut does, because when the mains go, the router, the shop wifi and eventually the mobile masts go with them. Every fallback route shares the same underlying dependency.
If accepting payment during an outage matters for your business, the questions to ask your payment provider are whether offline authorisation is enabled on your terminals, what the floor limit is, how long the terminal may hold transactions before it must upload them, and who carries the loss if one of those transactions is later rejected. The answers vary by provider and by country.
The gap this leaves
Put the pieces together and a picture appears. Cash machines need a connection. Card terminals need a connection for almost everything. Banking apps need a connection for absolutely everything. The entire consumer payment stack assumes a live link, and treats its absence as an error state rather than a normal condition.
For a large part of the world that assumption has never held, and in the rest it holds until the day it does not. That is the problem MobiBank is built around. Alongside the standard connected app, we are developing MobiBank's patented netless channel so that essential banking actions and payments work without an internet connection, starting with Alpha 1.
MobiBank is a banking platform designed for places and moments where connectivity cannot be assumed. The netless capability and the Alpha 1 device are currently in development.
Frequently asked questions
Do card machines need internet?
For almost every payment, yes. The terminal has to obtain an authorisation from the customer's bank, and that request needs a connection, whether fixed broadband, wifi or a mobile SIM inside the terminal. Chip cards allow a narrow exception for small offline approved payments, but most merchants are configured to require an online authorisation every time.
Can a card machine work on mobile data only?
Yes. Many portable and outdoor terminals contain their own SIM and use a mobile network instead of the shop's connection, which is why they work in a taxi, at a market stall or in a restaurant garden. It is a different physical route to the same destination, and it fails in the same way if the mobile network is down.
What happens if the terminal loses connection during a payment?
The transaction is not completed. The terminal times out and shows an error, and the sale has to be attempted again. A payment is only approved once the authorisation comes back, so an interrupted transaction normally leaves the customer with a temporary hold at most, which drops off when it is not confirmed.
Can I take card payments with no internet at all?
Only if your payment provider has enabled offline authorisation on your terminal, and only up to a floor limit, for a limited period, with the risk on you if a transaction is later rejected. It is worth asking your provider what your terminals are configured to do before you need to know.
Do contactless and phone wallets work offline?
Contactless card payments can be approved offline under the same rules as chip payments, within the local limits. Phone wallets add a further dependency, because the phone needs power and, in most configurations, has to be able to refresh its payment credentials periodically. A phone that has been offline for a long time may stop paying even before its battery dies.
Do card machines need WiFi?
They need a connection, not WiFi in particular. Countertop terminals typically use a fixed broadband line or ethernet, portable ones use WiFi, and mobile terminals use a SIM. Any of them will do, because what the terminal needs is a route to the acquirer and from there to the card issuer.
Can card machines work without internet?
For a limited window and at the merchant's risk. The terminal can approve small amounts under floor limits and rules the card scheme set in advance, then submit them once it reconnects. If the account was empty or the card was blocked, the payment is refused after the goods have already left the shop and the merchant carries the loss.
Do card readers need to be connected to work?
To get a genuine authorisation, yes. A reader that is offline is not checking anything with the bank, it is making a local judgement call using the chip's own counters and the scheme's floor limits. That is a deliberate fallback with a cost attached, not a connected payment.
Related
MobiBank is a Finnish financial technology company building a mobile banking platform for markets where connectivity and infrastructure cannot be assumed. This article is general information about payment infrastructure and is not financial advice.