Comcast has introduced a motion-sensing feature for millions of its newer Xfinity routers, letting customers receive alerts when movement is detected in their home while they are away. The free, opt-in feature, called Wi-Fi Motion, works by detecting disruptions to the household Wi-Fi signal rather than using cameras or dedicated sensors, and it matters because it turns existing home networking equipment into a basic security tool without extra hardware costs.

The feature is available on Xfinity gateways from the XB7 model onwards and must be manually switched on through the Xfinity app, where notifications are then sent. However, Comcast's terms state it may share data generated by Wi-Fi Motion with third parties without informing the customer, including in connection with law enforcement investigations, legal disputes involving Comcast, or court orders and subpoenas. This trade-off, first highlighted by The Verge, is a factor privacy-conscious users may want to weigh before enabling the tool.