For some Android mobile phone, please make sure the profile for Telephone Audio and Music Audio are activated : Settings - Bluetooth - Paired Devices - Avantree BTCK-10B(a setting symbol behind it) - Active both Telephone and Music profile.
What's more, you may need to reset 10BP if it is not working as expected. When it is reset to factory default settings, all the paired mobile phones information will be erased.
STEP 1 Make sure the 10BP is on. And your phone is disconnected from our 10BP.
STEP 2 Press and hold both V+ and V- for about 12 seconds until the LED flashes blue and red, then release the buttons.
STEP 3 Power off 10BP. After being powered on again, it will enter pairing mode automatically.
Below is the Video Guide about how to restore 10BP to default setting.