Prank, or nuisance calls, can come from a variety of sources, including telemarketers and even friends. If your phone is being called several times and each time you look at the caller ID, it shows that the number is withheld, you have a couple of choices to find out the annoying phone number. You will likely have to involve the police or obtain other legal assistance to find the number you are looking for.
Detail the times that you receive the calls and what days they occur. This will serve as a written record of how often you are being harassed.
Call your phone provider and inform them of the repeated calls you have been receiving from a withheld number. Ask the customer service representative to tell you the withheld number and any other information she has about it. You may not be able to get this information without a legal order, however. Each company's policies differ, so check with your phone provider for information about the particular way of handling nuisance and prank withheld number calls.
Contact your local police and see what procedures the department may have for consumers to follow. They may also be able to refer you to resources that will allow you to block your number from telemarketers' calls, such as the national Do Not Call Registry. If the problem is bad enough, the police may take a report from you and give you advice on getting a legal order for your phone company to turn information over to you about the withheld number, or they may help you to trace the call themselves.
Use programs and applications that route your call to a service provider that can unlock the withheld number. Some programs may use your cell phone to route anonymous calls to the service provider who can then finds out the caller's information and sends it back to your cell phone.
Your cell phone can be programmed to block withheld numbers, and you may be able to request from your land line phone provider to stop blocked numbers.
Be aware that some of these services may not follow all privacy laws. Be sure to verify the validity and legality of any service you use to track anonymous calls.