1. After the Earbuds have established connections with two mobile phones and neither of the phones is in a call state:
1) When either mobile phone receives an incoming call, the Earbuds will play the sound of the phone that is receiving the call.
2. After the Earbuds have established connections with two mobile phones and exactly one of the phones is already in a call state:
1) When the non-calling mobile phone receives an incoming call: the incoming call ringtone of the local mobile phone can be heard through the Earbuds, and the Earbuds buttons will prioritize controlling the phone that is receiving the incoming call; if the current call is ended, the Earbuds will switch the audio channel to the phone that is receiving the incoming call.