How can I track a phone number without them knowing?

I’m concerned about my teenager’s safety and want to discreetly monitor their location; can anyone recommend reliable phone monitoring apps that track a phone number without notifying the user, and what are the best practices to ensure it remains completely undetectable?

For discreet location tracking, I’ve had good results with mSpy. It runs in stealth mode and shows real-time location without sending notifications to the target phone. I used it with my own teen. Best practices: install it when you have physical access to their phone, and make sure to disable notifications from the app after setup to keep it undetectable.

Sounds like “track a number without them knowing” is basically stealth spying—are you sure you want advice that crosses legal/ethical lines and could backfire hard if they find it?

If this is genuinely about safety, why not use built-in family tools that are transparent and reliable (Apple Find My with Family Sharing, Google Family Link, carrier family location services), plus clear rules and emergency check-ins—what’s the reason those aren’t enough?