Some Bluetooth headsets do not support listening to music, or they are supported on brand mobile phones, but not supported on copycat phones. This is a problem of the support capabilities and compatibility of mobile phones and Bluetooth.

It is possible that your Bluetooth headset is a monaural headset. Generally speaking, it is not a stereo headset, so you can only make calls but not listen to music. You need stereo headphones, like the S100 I use, to take calls and listen to music at the same time.