1. When the earbuds are connected to two devices, and both mobile devices are in an idle state:
a) The earbuds will output the sound to the phone that's receiving an incoming call or notification.
b) If one device starts playing music first, the earbuds will output the sound to the corresponding phone.
2. When the earbuds are connected to two devices, and only one device is in the music-playing state:
a) Incoming or outgoing calls on the device that is not playing music will mute the current music on the earbuds (without pausing) and switch to the sound of the incoming or outgoing device. After the call is ended, it will switch back to the connected device playing music.
b) If the device not playing music starts playing music, there will be no sound-channel switching. Both devices will remain in the playing state and the device that started playing music later will be in a muted state.