Use the search engines to punch through the phone number online. If it belongs to the scammers, perhaps it has already published previous victims or law enforcement agencies to prevent criminal acts. Special attention always pay to short numbers, which is often used by cyber criminals. When sending a message or calling the same number from the account may disappear a large amount of funds. Be careful not to succumb to provocations, not acquainted with the terms of a subscription or making phone calls.
Search social networks where you are registered. They also have a search function. Thanks to her, you can not only find out why you annoying messages or calls from any numbers, but who is its owner. Perhaps trying to reach you distant relative or even someone close to you that changed your number. But the way to break a cell phone number online is not always effective, because users typically prefer to hide their contact details from other people.
Read the information on the website of your mobile operator. Sometimes on such resources published list of numbers of scams, as well as other information about the activities of the intruders for the last time. Also here you can activate the service of recognition procedure if it is disabled, and the phone screen is not displayed the caller.