Oh really? vậy hả / thế à

Vậy hả? is how you react to news: "Oh really?" or "Is that so?" It shows you're listening and a little surprised, and it invites the other person to go on: Mai em về quê rồi. I'm going back to my hometown tomorrow. Vậy hả? Đi mấy ngày? Oh really? For how many days? In Hà Nội it's Thế à?

In Saigon Vậy à? is common too, and said quietly it can just mean "Oh, I see": Vậy à, em hiểu rồi. With someone older, add their word: Vậy hả chị?

For more surprise, say Thật hả? Really? (in Saigon speech often Thiệt hả?, in Hà Nội Thật à?). Vậy sao? sounds more surprised still, and sometimes doubtful.

You know hả and à after a statement, to check what you've just heard: Em nghỉ việc hả? You quit your job? Vậy hả? does the same without repeating anything, because vậy (in Hà Nội, thế) stands for whatever was just said.

To answer, say dạ, ừ or đúng rồi, and usually a little more of the news.