“Hello. Could I speak to Sue, please?” or “Hello. Could I talk to Sue, please?”? Which one is correct?

Question

This page says:

When you make a telephone call, you ask if you can speak to someone. You don't ask if you can 'talk to' them.

Hello. Could I speak to Sue, please?

But in fact, a lot of native people says

Hello. Could I talk to Sue, please?

See this English teaching video at 4:22

"Can I talk to Phil Watson, please?"

So, who is right?

"Hello. Could I speak to Sue, please?" or "Hello. Could I talk to Sue, please?"? Which one is correct?

Answer 1

Both are correct. However, you might try, "Hello. May I speak with Sue, please?" Better is, "Hello, this is Tom Smith. Is Sue available to speak with?" (This is a matter of etiquette, not grammar.)

Answer 2

The fact you said "Hello." and "please" indicates a formal context.

To stay consistent, so you should use may and speak. talk is kind of like chat and more informal. So:

Hello. May I speak with Sue, please?

(AmE disclaimer)