#1 When I was speaking to Rani over the phone suddenly we were cut off/hung up?

which one is correct? and When to use hung up and cut off?

thank you
"Cut off" means that the connection dropped when both of you were still having a conversation. It's in the passive here ("were cut off") indicating that you don't know who broke the connection.

The active form isn't used for interrupted telephone conversations. If you know who ended the conversation abruptly, use "hang up."

I was speaking to Rani over the phone when suddenly she hung up on me.

The active form is appropriate for face-to-face conversation.

I was speaking to Rani when she cut me off in mid-sentence.

cut off