HSP Profile not working on connecting via Android Settings Dialog

I am a newbie on bluetooth & facing a few basic problems. I am currently working on an android voice assistant application, trying to make it work with bluetooth headsets. If I connect to bluetooth via settings dialog the voice is still captured from Phone's microphone(and not from headset) but when it's connected via HSP profile programatically, voice is captured from Headset. Can anyone help me understand this behaviour?