Why your POS has to work offline — load-shedding, dead routers and lost sales

Friday night, the restaurant is full, and the router dies. Or the light goes and the UPS keeps the till alive but not the internet. What does your POS do?

For a lot of "cloud" POS software the honest answer is: it stops. The screen spins, the customer waits, and the cashier writes the bill on paper — which is exactly the record you bought a POS to get rid of.

Three kinds of POS, and what each does offline

Online-only. Every price, every sale and every receipt comes from a server. No connection, no sale. Fine in a country with perfect internet; a liability anywhere else.

"Offline mode" that is really a queue. The till lets you keep ringing, but it cannot work out the price properly, cannot print a proper receipt, or loses track of tax and discounts until it reconnects. Better than nothing, but the paper still comes out.

A till that genuinely works offline. It keeps a copy of your menu, prices, taxes and offers, works out the bill itself, prints the real receipt, takes the money — and sends everything up when the connection comes back.

Only the third one is worth having.

What "works offline" should really mean

When you ask a supplier whether their POS works offline, ask about each of these:

1. Does it price the bill correctly? Tax at the right rate for cash or card, discounts, deals and options — all without the server.
2. Does it print a proper receipt? With a reference number, and the real bill number on any reprint once it syncs.
3. Can a cashier sign in? If the till restarts during an outage, can somebody who has signed in before get back in?
4. Can it park a table? A restaurant needs to hold a table's order and settle it later, even with no connection.
5. Does the kitchen still get its slip? The cooks should not have to wait for the internet.
6. Is a sale ever sent twice? A connection that dies halfway through an upload is the classic way to charge a customer twice. Every sale should carry its own key so a retry finds the sale already made.
7. What refuses to work, and does it say so? Some things genuinely need the server — a promo code with a usage cap, a credit limit. The till should say so in a sentence, not show a button that does nothing.
8. Does the day close wait for unsent sales? If one till is still holding takings, closing the day should refuse and name that till. A Z report that does not add up is worse than no Z report.
9. How old a price list will it sell on? A till that has been offline for two days should stop selling on last week's prices.

What about tax filing?

If your business files invoices with FBR, PRA or SRB, the invoice cannot reach the authority while you are offline. A good system takes the money and prints the receipt anyway, then files the invoice the moment the sale reaches the server — and a reprint carries the authority's number. See our guides to FBR, PRA and SRB.

Hardware matters too

• Run the till on something with a battery or a UPS — a Sunmi terminal, a tablet or a laptop-style PC.
• Use a 4G dongle or a phone hotspot as a backup connection for the till you care most about.
• Keep the receipt printer on the same UPS as the till.

How Sellify does it

The Sellify till on Android and Windows keeps your menu, prices, taxes, offers and printers on the device. Offline it prices the cart, prints the receipt and the kitchen slip, parks tables, lets a cashier who has signed in before sign in again, and queues every sale with its own key. When the connection returns, everything goes up, the server checks every price again, and anything that disagrees is flagged for a manager rather than quietly absorbed.

Read the details on Offline & Android, or book a demo and we will pull the network cable while you ring a sale.