When someone calls repeatedly and hangs up, it could be a major nuisance. It could be some one previously known to you. Try blocking the number. If ID is hidden, contact your network for help. If none of these work, contact police.  

Keep in mind that there are scammers who want you to call them back and play tricks on you.  They may use computerized caller devices which make automated calls to thousands of numbers. When you call back, either a call center robot or a human would attend the call.  Unless you are absolutely certain who you are talking with, disconnect the call. 

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