Is it possible to somehow control the call during the call?

Question

Android

I am not very familiar with android programming. I read several books, but I still have not figured out whether it is possible to control the call during a call. That is, the call has already been initialized and started, and I want to send a DTMF signal to the interlocutor. It's easy to do this with pens, you type stupidly through the dialer, but is it possible to do the same actions programmatically? It is also interesting whether it is possible for the program to listen to the incoming signal. As far as I know, almost all voice recorder implementations require root during recording. I like this way too.
If there is a book, reading of which will remove my questions, I will be glad to read it. If you can tell me where to dig too.

Answer 1

dtmf android example
android record call programmatically