NPG National Principal Group XXXX has been calling my cell phone several times a day leaving screaming messages, threatening to use any means necessary to find a family member of mine. They use a recording to state the family member name they are looking for but the rest of the message is live. They state I need to call them right now and provide them the information they seek regarding this family member or they will continue to use any means necessary to locate this person. I called them, a woman answered when I asked for her name and her company name because she just picked up the phone with " hello '' she began screaming at me wanting me to give her my cell phone number. I told her I was n't giving any information until I knew who she was and what company. She said XXXX and NPG. I asked what NPG stood for and she screamed at me stating I needed to allow her to assist me by giving her the information she asked for or she would disconnect. She stated I better let her assist me or she was disconnecting then counted to XXXX and hung up. I called back she answered again. I told her she could tell me what her company name was and why she would be looking for a family member or I would not help her. She then said she could not tell me the " plethora '' of things her company did. I asked what NPG stood for and she finally gave me National Principal Group. I again asked why they would be calling me about a family member. She stated she could n't tell me that until I gave her the family member name or my cell phone. I told her I ca n't give her anything until she tells me what her company does, she again refused to tell me what her company does. I said well then I ca n't help you with the information you seek from me and I hung up.