How should we use simple past after present perfect?

Question

Is this sentence correct?

I have called him but he did not answer.

Is there any other way to say it?

What about these two?

I am calling him but he will not answer.

I am calling him but he is not answering.

Answer 1

I have called him but he hasn't answered (yet). This is present perfect and the fact that you have called him (in the recent past) and the person hasn't answered (until this moment) is important to you in the present.

I called him but he didn't answer. Past simple, both the call and the fact he didn't answer happened in the past and have no present consequence.

I am calling but he is not answering. Present continuous: the calling is happening at this moment.

I will call him but he won't answer. This will happen in the future.