Smartphones (851713) are cellular-network-capable devices whose principal function is telephony, even if they also perform computing tasks. Tablet computers whose principal function is data processing — and which may or may not have cellular capability — are generally classified under the automatic data-processing machines heading rather than 8517. The principal-function test and the device's design intent are the deciding factors; CBP has issued binding rulings on specific models.

Wi-Fi routers and managed switches that receive, convert, and retransmit data signals are generally classified under 851762 as machines for the reception, conversion, transmission, or regeneration of voice, images, or data. However, if a device's principal function is automatic data processing rather than signal routing, it may fall under the ADP heading. The distinction turns on whether the device processes data or routes/converts signals, and binding rulings are available from CBP for specific products.