"Both iOS and Android...transmit telemetry data to their motherships even when a user hasn’t logged in or has explicitly configured privacy settings to opt out of such collection. Both OSes also send data to Apple and Google when a user does simple things such as inserting a SIM card or browsing the handset settings screen. Even when idle, each device connects to its back-end server on average every 4.5 minutes...In the US alone, Android collectively gathers about 1.3TB of data every 12 hours. During the same period, iOS collects about 5.8GB."
https://arstechnica.com/gadgets/2021/03/android-sends-20x-mo...