Comment by tsimionescu

Actually, the second answer is also unnecessary. The conversation can go like this:

A: Can you hear me?

B: Yes

A: What time is it?

B: 5 o'clock

A: Thank you, goodbye!

B: Goobye!

Nothing is lost compared to:

A: Can you hear me?

B: Yes

A: Yes

A: What time is it?

[...]