Does it hurt to be polite on the phone?

Say you get a call from someone within the same organization.
But the organization is huge and you don't quite know everybody.
The caller introduced herself as so-and-so, and you scratched your head, trying to recall who she really is. As in - which department and her position.
You don't know her, you can't remember her name, she's asking about something very trivial and she sounds young.
So, does it hurt to be polite to her on the phone?
Just because you don't know her it does not mean that she's more junior than you and you can treat her lightly.
She happens to be your senior - in age, and in rank.
But she knows better than to start pulling rank, only that she hopes that you will learn one day.
That it won't hurt to be polite on the phone to a stranger.
If the caller is in fact your senior, then it is only expected for you to be polite to her
But even if the caller is (so-called) beneath you in terms of rank, it'll earn you extra cookie points.
Because being polite and gentle won't kill.
Sometimes, it's proof that one is well brought up, not merely well educated or well promoted.