Does it support extensions?

Yes. Append `;ext=1234` to the number — the tel: format passes it through to the dialer, which most modern phones honor.

Why not just print the number?

A QR removes the typing step. It is also more usable in low-vision contexts and at distance — the camera can read it from across a counter.

PLATE 07

SCALE 1 : 1

EDITION v0.26.10

FILE KMK·QR·07

FIGURE A · PHONE ENCODE

Free phone QR code generator

Encode a phone number into a QR. Scanning offers a one-tap dial. tel: format, supported by every camera that scans QR codes.

Create QR code

process: client-side · zero upload
cost: free · no signup · no expiry
format: PNG · SVG · PDF
license: MIT · open source

§01

Notes on the artifact

A phone QR encodes a tel: URL — the same format used by clickable phone numbers in HTML. Scanning offers a "Call <number>" prompt. The user has to confirm; phones do not silently dial from a QR.

Include the country code (+1 for the US, +44 for the UK, etc.) so the QR works regardless of where it is scanned. A national-format number works locally but fails when a traveler scans it.

Use for service stickers ("Tap to call support"), business cards where dialing matters more than messaging, and accessibility cases where typing the number is awkward.

§02

Footnotes & queries

Does it support extensions?: Yes. Append `;ext=1234` to the number — the tel: format passes it through to the dialer, which most modern phones honor.
Why not just print the number?: A QR removes the typing step. It is also more usable in low-vision contexts and at distance — the camera can read it from across a counter.

§03

Anatomy of the code

QR ANATOMY FUNCTIONAL REGIONS DRAFTING SCHEMATIC

Every QR code is a part-functional, part-data grid. Three finder patterns at the corners let a scanner lock orientation; an alignment pattern at the bottom-right corrects perspective skew when the code is photographed at an angle. The timing patterns — alternating modules running between the finders — tell the scanner the cell pitch. Format info encodes the error-correction level and mask pattern across 15 bits arranged in an L-shape. The rest of the grid is the payload — data plus Reed–Solomon error-correction codewords. The quiet zone is mandatory whitespace; without four clear modules of margin, scanners reject the code. The detail below the main figure shows the finder pattern's 1·1·3·1·1 ring construction — proportions deliberately chosen so a scanner can recognise the pattern at any rotation, with three patterns at three corners triangulating the code's orientation.

§04