What we want to do

I want to send voice one way even on the lock screen.

What we tried

Adopt a recorded sound source for notifications

　This method did not work. temtem plays the sound in real time when it is connected to the phone in the first place.

Something that utilizes live activity

　Live activity of push notification is taken by the authority (a feature from iOS 17.2).

LiveKit also did not join the call from the background. I found a theory that LiveKit uses this push to talk framework, but it seems that LiveKit cannot join a call in the background either.

It's a mystery why it works even if the call duration is infinite or if you don't have notification privileges.