Cách sử dụng
The expression "be on the telephone" means to be using a telephone to talk to someone else. This expression is used when you want to let someone know that the person they are trying to reach is currently talking to someone else who is not in the same room. For example, if someone calls you and you are already talking to someone on the phone, you can say "sorry, I can't talk right now, I'm on the telephone."