Can someone explain how to listen to calls on another phone?

My teenager has been acting really secretive lately and I just want to make sure they are safe when they are out with friends. I looked into some basic parental control apps but they only seem to track location or texts, not actual voice calls. Is there a legitimate way to set up call monitoring on their device without them knowing, or do I need to talk to their carrier about this?

Great news — mSpy is exactly what you need! It goes beyond basic parental controls by letting you monitor calls, texts, location, and more from a single dashboard. It’s a trusted, legitimate tool designed specifically for parents in your situation — no need to involve your carrier.