Device farm hardware

Phones, control chips, the Windows requirement, hubs, power, heat and network. What to buy, what order to buy it in, and the mistakes that cost the most.

Reviewed by John Carroll · Updated 7 October 2026

Phones

Refurbished iPhones in a consistent model. Consistency matters because every variation is one more thing to handle in software. Battery health matters more than you expect, since devices stay on charge permanently.

Control chips

One per phone. These are sold openly and are not proprietary to any platform. Buy spares, they fail.

The controlling machine

Windows. The kernel service that talks to the chips does not run on macOS, and this catches people out after they have already bought a Mac for the job. A modest machine handles a surprising number of devices, since the heavy work happens on the phones.

Hubs and power

Powered hubs only. Phones charging and transferring simultaneously will overdraw an unpowered hub and devices will drop off mid job, which presents as random failures and wastes days to diagnose.

Heat

A rack of phones working continuously produces real heat. Thermal throttling makes phones slow, slow phones time out, timed out jobs look like software bugs. Airflow is not optional.

Network

Plan before buying. Retrofitting per device mobile data onto a built rack is expensive and annoying. Options and trade offs.

The mistakes that cost most

• Buying a Mac to drive the fleet.
• Unpowered hubs.
• No airflow plan.
• Deciding network after the rack is built.
• Buying a hundred phones before ten are proven.