Every shop has the moment: the owner is away, or the electricity is, and a customer is standing at the counter. The computer holds the stock, the prices and the bill book, and the computer is off. This article explains how Layerdots handles that moment, including the one problem most people never think about until it bites: who decides the invoice number when two devices can both make bills.
Two ways the phone bills, for two different situations
When the PC is on, the phone works as a companion over the shop WiFi. Pairing is a QR code on the computer screen; after that the phone searches stock from the aisle, scans barcodes, photographs supplier invoices, and makes bills that save straight into the computer, printing from it like any other bill. No internet is needed for this, only the shop's own WiFi.
When the PC is off, the phone switches to the shop's secure cloud copy. It can still look up items and prices, still make a proper GST bill, and still respect credit limits. When the computer comes back on, everything the phone did flows into it, and the books read as if the shop never paused.
The invoice number problem
Here is the trap in every two-device setup. GST expects your invoice numbers to run in one clean series, with each number used once in a financial year. Now imagine the PC is issuing numbers from its own counter, and the phone from its own memory of that counter. Sooner or later both hand out the same number, and you discover it only when the books and the GSTR-1 disagree.
Layerdots avoids this the only way it can actually be avoided: when phone billing is on, there is exactly one number series, kept in the shop's cloud account, and both devices take their next number from it at the moment of saving. Not a copy each, one counter. Two bills can be saved in the same second from two devices and they still come out as consecutive numbers, never the same one.
It also respects how you number your bills
Shops number bills differently. Some let the software count: 101, 102, 103. Some jump the series forward when a new book starts. Some type every number by hand, Tally style, in shapes like 2026-27/001. Layerdots supports all three on the computer. While phone billing is switched on, the shared cloud counter runs the automatic series, and that single counter is exactly what makes a duplicate impossible when two devices are billing at once. Typed and jumped series are how the PC numbers whenever phone billing is off.
Cancelled bills keep their numbers, the new financial year starts its own series in April, and the GSTR-1 documents summary reports what actually exists. The numbering rules are the shop's responsibility in law, but they should be the software's job in practice. If you want the details of those rules, we wrote them up separately: can you reuse a cancelled invoice number?
What the phone can do, concretely
- Bill with GST, customer, discounts and payment mode, PC on or off.
- Check stock and prices from the aisle, with batch and expiry for medical stores.
- Scan supplier invoices with the camera; the items land in the computer's purchase entry for review.
- Share the bill on WhatsApp to the customer's number.
- Respect permissions: staff logins carry the same roles as on the PC, and deletions can be protected by the shop's delete password.
What it deliberately does not do
The phone is not a second, separate shop. It does not keep its own private books that need reconciling with the computer later, and it cannot bill offline while the PC is also billing offline, because that is exactly the situation that produces duplicate invoice numbers. One shop, one set of books, one number series. Everything else follows from that.
Common questions
Does the phone need internet to bill?
With the PC on, no: the shop WiFi is enough. With the PC off, yes: the phone works against the
shop's cloud copy, and the shared number series needs the internet to be shared.
Will phone bills mess up my stock?
No. A phone bill reduces stock in the same books the PC uses. When the PC comes back online, the
bills the phone made are already part of its history.
Can my staff use it without seeing everything?
Yes. Staff sign in with their own login and see what their role allows, same as on the computer.
Which phones does it support?
Android and iPhone. Pairing takes a QR code and a minute.