Not without rapid depletion of the battery, which you would notice. The only thing that your cell phone does that you could consider spying is pinging the tower every few seconds in order to maintain the registration, and pass it to the next tower if you are moving.
I agree with you, but I have no other explanation for the personal examples I provided. And those aren’t the only examples I’ve encountered. They’re far too specific, and too frequent, to be mere coincidence.
I’m also not talking about the phone alone, but “listening” across all your devices. There’s a identifying connectivity there, and one that I’ve never consented to.
If the phone were acting as a microphone uplink you would notice a lot of battery drain. However the phone could contain enough software that it could listen to you and record then compress and send data in short bursts. What if you take a couple of hours of listening to your house then deleting all the silence then compressing the sound portion and spreading the actual content of the sound into 8 tracks and sending them simultaneously. You could probably upload several hours of voice in a couple of seconds. Siri is always listening.