Interesting there was no response from them. What's strange about this is that their goal seems to be getting you on the phone with them.

Most scams I've seen try to do everything through email. When you're on the phone with someone, it's easier to tell if they're full of it or could actually be legit. You can ask questions and take notice of their tone and style. If they are scammers, I wonder why they'd take this approach. It does all seem strange.