Communication carriers have a strict confidentiality system, it is not possible to easily leak the customer's information casually. Unless it is an insider, and this is a technical job, it is estimated that the chances of finding out the whistleblower through this method are smaller. If the target of the report is the public security department, or the reported person is involved with the public security department, you can go to the communications operator to check the information of the informant.
Despite the fact that the other side of this practice is illegal, but , in order to be safe, it is recommended to report through the public phone.