Implementation of loudspeaker, hold, mute, conference like basic functionalities

[csetanmayjain]

I like your efforts, and would like if you take it to next level. I try to develop calling screen with basic functionalities like loudspeaker, hold, mute, conference, etc. It's possible to access these privileges by making our own default dialer. I successfully implemented this but can't able to implement these basic functionalities. Can someone help me? Thanks.