Please check the following points:
1) Check if the earbuds are operating
2) Check if the earbuds volume are at an appropriate level
3) Check if the earbuds are correctly connected to your mobile phone.
4) Check if the earbuds are operating within a normal working range.
Why the call quality of these earbuds is poor?
Please make sure:
1) Whether your mobile phone is in an area with a strong signal.
2) The earbuds are within an effective distance (10m) without any obstacles between the earbuds and mobile phone.
Why can't I control my earbuds?
Please ensure the paired device support AVRCP (Audio Video Remote Control Profile) profile.