How to Find Out the Number of a Withheld Call Written by leyla norman | Translated by ehow contributor Ask your phone company to trace the withheld call. 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. Skill level: Moderately Easy Instructions 1 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. 2 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. 3 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,