Just try to call back to the subscriber, to identify a person by phone number. Of course, better to do it with another SIM card or even from a landline, then he will not have any suspicion about your identity. Think of any legend and introduce yourself, for example, an employee of social surveys. Ask the source and get the necessary information about his personality.
Find out what city could be registered you are interested in the room. It can enter the first 3-4 digits that are the code of the operator of cellular communication and change depending on city or region. The full list of codes of operators you can find on their official web pages.
Contact pay point mobile communications operator, if you know that the number is registered in your city. They usually have information about subscribers. To find out who owns a phone number, you will need to come up with a believable legend, for example, that you have found a SIM card and now want to return to its owner. Use this method in the least because, first, lying is bad, and, secondly, your meticulousness could cause suspicion among the staff, and they will report you to law enforcement authorities.
Enter the phone number in any of the search engines. Also try to do the same thing in social media or on free classified ads website. Perhaps the number has already been used to register for any resource, or its owner placed an ad specifying the coordinates for communication. It's also possible that you will encounter fraudulent website, using this number to spam.
Read the information on the website of your mobile operator. Currently, companies offer a variety of paid services that allows you to obtain summary information about the subscriber, although he usually must confirm the operation. In addition, note free phone numbers on the Internet. Although they often offer outdated information, often it helps to identify a person by phone number.
To apply to law enforcement if the calls and messages from an unknown caller, do not stop. Such actions are punishable by law, so police will help you to establish the identity of the subscriber and resolve the problem.