Lantum Software Developer interview questions

I was contacted by a recruiter and when I was asked "What is your current salary ?" I've refused to answer and only told him my expected salary, then recruiter start to put pressure on me by asking again and again the same question and told me that I have to answer this. The only thing that outlined recruiter's lack of professionalism was his words" why you don't want to answer, is it because you are underpaid?", so rude. For me this company is forever in a black list.