Your phone is in constant communication with servers, apps, and services — most of it invisible to you. Some of this is necessary. A lot of it is data collection that happens by default. Here’s what’s actually going out and what you can do about it.
Location data
Location is the most valuable and most widely collected data on phones. Your phone tracks location via GPS, Wi-Fi networks nearby, cell tower triangulation, and Bluetooth signals. Many apps that don’t obviously need your location have it enabled — weather apps, shopping apps, games, and social media all commonly request and use location data.
This data is often sold to data brokers and location analytics companies. A 2018 New York Times investigation found that some apps sold location data precise enough to track someone from home to work, to a church, to a psychiatrist’s office — without any one piece of the data appearing sensitive on its own.
Check it: on iPhone go to Settings → Privacy & Security → Location Services. On Android: Settings → Location → App permissions. Set anything that doesn’t genuinely need location to “Never.” Reduce “Always” permissions to “While Using” where possible. Most apps work fine without persistent location access.
App usage and behavior data
Most apps collect telemetry: which features you use, how long you use them, what you tap, what you search for within the app. This is often framed as “improving your experience” in privacy policies. In practice, it’s behavioral profiling used to improve ad targeting and increase engagement.
On iPhone: Settings → Privacy & Security → Tracking shows which apps have requested permission to track you across other apps and sites. Turn this off globally: Settings → Privacy & Security → Tracking → toggle off “Allow Apps to Request to Track.” On Android, there’s no equivalent single toggle — you have to manage it per app, or use a browser extension like uBlock Origin to reduce cross-site tracking in mobile browsers.
Contacts, microphone, and camera access
Apps frequently request access to contacts, microphone, and camera beyond what they need. A ride-sharing app needs your location, not your contacts. A shopping app doesn’t need your microphone. When an app requests permissions it doesn’t clearly need, that access is often used for data collection.
Review these in the same Privacy & Security settings. For microphone and camera especially, set anything non-obvious to “Never.” You’ll get a permission prompt again if you use a feature that genuinely needs it — at which point you can make an informed decision.
What your phone sends even when idle
Background app refresh allows apps to receive data and update content while you’re not using them. It also means they’re sending data while you’re not actively using them — reporting location, syncing behavior, checking in with advertising servers. On iPhone: Settings → General → Background App Refresh → turn off for apps that don’t need real-time updates (most apps don’t). On Android: Settings → Apps → select an app → Battery → Background usage.
Your phone also sends data to Apple or Google about app crashes, usage statistics, and diagnostics. On iPhone: Settings → Privacy & Security → Analytics & Improvements → turn off “Share iPhone Analytics.” On Android: Settings → Privacy → Usage & diagnostics → turn off.
Advertising identifiers
Both iOS and Android assign your phone an advertising ID — a unique identifier that lets advertisers track your behavior across apps without using your personal information. You can reset this ID periodically (which breaks the continuity of your profile) or disable it entirely.
On iPhone (iOS 14.5+): you have to opt out of tracking per app — go to Settings → Privacy & Security → Tracking → disable “Allow Apps to Request to Track” globally. On Android: Settings → Privacy → Ads → select “Delete advertising ID” or “Opt out of Ads Personalization.”
The bottom line
You can’t stop all data collection — some of it is baked into the operating system. But auditing app permissions, disabling tracking requests, turning off background refresh for apps that don’t need it, and deleting your advertising ID cuts the data flow significantly. These aren’t one-time changes; worth revisiting every few months as you install new apps.