Someone randomly speaking through my phone??!

This morning I started hearing little boys talk through my Airpods, and then through my iPhone 15 Pro Max (iOS 18.3.2). My phone is al stock (so no jailbreak), also:

• ⁠Latest update • ⁠Private network • ⁠Nothing weird (like unknown apps) in either screen time, battery usage, privacy (microphone, camera etc. all turned off), notification 'history' • ⁠Live listen, VoiceOver turned off. • ⁠Did have AirDrop enabled, but just for friends (these were not friends or anyone I knew). • ⁠Bluetooth enabled, just for Apple Watch, nothing else connected according to settings. • ⁠Walkie Talkie disabled on Apple watch

It starts with a kind of pling sound, but I was not able to record it, because it is at random through the day (will try to do it). After the pling sound I hear some children talking through my phonepiece (upper speaker), something like:

Boy 1: pling " James do you hear me" Boy 2 responding: pling "Yeah I hear you".

This has been happening randomly for the last couple of hours (2 moments of about 5 min. in which I hear the bleeps, two times I heard the voices). Even when my phone is off. They don't seem to hear me or react when I say something back, but I'm still really worried/freaked out about my privacy!

I have found multiple of these situations online, but none of them had a solution. I restarted the phone now, hoping it will not happen again. Any other suggestions or experiences like this and if they went away automatically?

SOLVED: Another user pointed out a walkietalkie function in teams having an alert. We just recently started using it and I never knew how it worked. Turned off the alert sound and it has not been happening anymore. Still confused as they were kids, but maybe a coworkers kid was playing with it. The alert sound I heard was exactly this one: https://www.youtube.com/watch?v=UhsJGLnO_Xg (2:02 min.)