Both iOS and Google Android transmit telemetry, despite the user explicitly opting out of this. However, Google collects a notably larger volume of handset data than Apple. During the first 10 minutes of startup the Pixel handset sends around 1MB of data is sent to Google compared with the iPhone sending around 42KB of data to Apple. When the handsets are sitting idle the Pixel sends roughly 1MB of data to Google every 12 hours compared with the iPhone sending 52KB to Apple i.e., Google collects around 20 times more handset data than Apple. In 2020 it is estimated that in the US there are 113M iPhone users and 129M Android users. Assuming all of the Android users have Google Play Services enabled then scaling up our measurements suggests that in the US alone

Apple collects around 5.8GB of handset data every 12 hours while Google collects around 1.3TB of handset data. When the handset is idle the average time between iOS connections to Apple is 264 seconds, while Google Android connects to Google on average every 255 seconds i.e. both operating systems connect to their back-end servers on average every 4.5 minutes even when the handset is not being used. With both iOS and Google Android inserting a SIM into the handset generates connections that share the SIM details with Apple/Google. Simply browsing the handset settings screen generates multiple network connections to Apple/Google.

A number of the pre-installed apps/services are also observed to make network connections, despite never having been opened or used. In particular, on iOS these include Siri, Safari and iCloud and on Google Android these include the Youtube app, Chrome, Google Docs, Safetyhub, Google Messaging, the Clock and the Google Searchbar.

More in https://www.scss.tcd.ie/doug.leith/apple_google.pdf