Help Bluetooth speaker issue with galaxy s2


I have a bluetooth speaker(DBest 4501 mini) through which I can play the mobile music fine. But I am unable to get any call output on the speaker. The call is audible only on the phone speaker. If I try to choose the bluetooth headset icon during a call, it says no bluetooth device found, though the speaker is connected and was playing music. Is it really impossible to get the call on the speaker? Any help or tips will be appreciated.