A card machine sends an authorisation request to your acquirer, which routes it to the customer's bank and returns an answer in about two seconds. The money arrives later, in a settlement batch, net of the merchant service charge. Between those two events sit several charges, and only one of them is the percentage on the advertising.
Authorisation, batch, settlement
Authorisation reserves the funds. At the end of the day the terminal or the provider submits a batch, and settlement moves the money, usually the next working day. Some providers sell faster settlement as a paid feature, which is exactly how Lopay structures its account tiers. A refund runs the same path in reverse and takes longer to appear on the customer's statement.
Connectivity, including the old kind
GPRS machines use a mobile data connection of their own rather than wifi, which is why market traders and mobile trades have used them for years. Current equivalents use 4G. Terminals that dialled out over a phone line are being retired as the copper network is switched off, so a machine that needs a landline is close to the end of its supported life.
Running one on a first shift
Enter the amount, present the machine, let the customer tap or insert, wait for the approval and hand over the receipt. The two things new staff get wrong are typing the amount in pounds rather than pence on machines that expect pence, and cancelling a slow authorisation that was about to succeed. Both are worth ten minutes of training before a busy service.
Questions people ask about how do card machines work
What charges apply to each card machine transaction?
The merchant service charge as a percentage, often a fixed pence element, and at some acquirers a separate authorisation fee. Chargebacks and refunds may carry their own charges, which are published in the provider's fee schedule.
Do card machines work without an internet connection?
They need some connection: wifi, a SIM or a paired phone with signal. Some support an offline mode that stores a sale for later authorisation, which moves the risk of a decline to you.
Are GPRS card machines still sold?
The mobile data principle is, in the form of 4G terminals. GPRS as such is a legacy technology and buying into it now is buying into an ageing network, so ask what generation of mobile connectivity a machine uses.