Making obscene telephone calls for sexual pleasure is known as telephone scatalogia and is theorized as a form of exhibitionism. It is usually classed as a paraphilia from a medical viewpoint, although from the viewpoint of the recipient of the calls, it is generally considered to be both a form of sexual harassment and a form of stalking. In some US states, making obscene telephone calls is a Class 1 Misdemeanor.
Generally, recipients of obscene phone calls are advised to simply hang up on obscene callers, and to report the incident to the telephone company and/or the police. Even where Caller ID is not available, calls are logged by the telephone company, so the perpetrator's phone number can be discovered. However, many people who regularly engage in obscene phone calls use payphones or prepaid cell phones, and in these cases a more extensive investigation is necessary.