I tried almost everything of my capability and even learned a lot in this process. I think this project could only be completed by a experienced coder.
The above code works only on my “ASUS ZenFone Lite L1” and is unable to serve its purpose on any other phone tested by me (approx 14 mobile).
According to my research
Google assistant with voice command “Call -xyz- on loudspeaker” works very well. It is working means we could achieve that. That’s why I tried using Intent. But, you know the result… and I tried almost 15 playstore & 5 other source apps but failed to resolve the issue.
I am waiting for someone who can help me as soon as possible…
And thanks a lot for your precious time and help @Taifun