Here is the disappointment nobody warns you about: you got phone printing working, and scanning still does not. That is not a setting you missed. A multifunction printer is two devices in one box, and the phone route that unlocked one of them usually leaves the other locked. Here is the honest map.
Printing sends data one way — phone to paper. Scanning runs the other way and needs a different conversation: the phone must control the scanner mechanism and pull an image back. USB printing apps are built for the first conversation. A few support scanning on selected multifunction models (PrintHand, for example, advertises direct mobile scanning for selected MFPs), but broad USB scanning support for phones simply does not exist the way printing support does. These are the routes that genuinely work.
Printer makers publish page languages that apps can implement once and reuse across hundreds of models. Scanner control over USB never standardised the same way for phones, so each model is its own project. That is why an app can honestly list your printer as supported and mean printing only. Read support lists with that lens: unless scanning is named, it is not included.
If your multifunction has Wi-Fi (check — many do, even when you bought it 'for USB'), the maker's own app — HP Smart, Canon PRINT, Epson iPrint, Brother iPrint&Scan — usually scans straight to the phone properly, because the maker wrote it for that exact hardware. This is the only phone-scanning route that feels like a product rather than a trick.
The unfashionable route that never fails: scan on the connected PC (where the full driver suite already works), save as PDF, and send the file to the phone by cable, chat, email or shared folder. Thirty extra seconds, zero compatibility roulette. In offices, scanning to a shared folder on the PC is the same idea with the phone fetching the file when it wants it.
For documents — signed pages, forms, receipts, ID proofs — a camera scan app (the scanner built into Google Drive, Microsoft Lens, or your phone maker's notes app) produces a clean, straightened PDF that beats a dusty flatbed for everyday paperwork. It is not a substitute for photo scanning or fragile originals, but for office paper it is honestly the fastest scanner you own.
The full phone-to-USB-printer method, shown live with the cable, the app and a real print.
▶️ Watch Full VideoSome apps show the scan feature and support it only on selected multifunction models, usually over Wi-Fi. If your model is not in that smaller list, the button leads nowhere. It is a support-list issue, not something a reinstall or a different cable will cure.
On a small number of models with the right app, yes — treat it as a bonus when it works, never as a promise. The printing support list and the scanning support list for the same app are different lists, and the scanning one is much shorter.
Scan once to the PC or a shared folder using the full driver (with the document feeder doing the work), then let the phone pick up the finished PDF. Feeder scanning belongs on the machine built for it; the phone's job is receiving the file, not driving the mechanism page by page.