An Engadget guide explains how to repurpose an old, unused smartphone as a home security camera rather than binning or recycling it. The process takes only a few minutes using the free, cross-platform app AlfredCamera, requires no special technical skills or wiring beyond a charger, and offers a cost-free alternative to buying dedicated security hardware.

Users install AlfredCamera on both their main phone and the old device, then pair them via a shared account or QR code, setting the old phone to "Camera" mode and the main one to "Viewer". The free tier includes a siren alarm, low-light mode, two-way talk and support for two cameras, while paid plans (from $5.99 a month) add HD streaming, longer recording loops, cloud storage and up to unlimited cameras. The article also recommends keeping the old phone plugged in, disabling battery optimisation for the app, factory resetting the device beforehand for privacy and storage reasons, and weatherproofing it if placed outdoors.