- Could you speak up, please?
- Could you speak a little louder, please?
- Sorry, I don't know what _________ means?
- Could you give me some more details, please?
- Could you expand on that, please? (more formal)
- Sorry, it's a bad line. I can't hear you.
- Let me check if I've got this right
- Could I just confirm what you've told me?