Restricted phone numbers do not show up on phone bills. Telephone carriers cite privacy concerns as the reason they cannot share these numbers with customers. Customers who do not wish to receive these calls can choose to block all restricted numbers.
By law, toll-free numbers and emergency services numbers have the right to see all numbers that call them, including restricted numbers. Third-party services that allow consumers to trace restricted calls do so by forwarding them to a toll-free number. When the call connects to the toll-free number, the restriction no longer works and the number is displayed to a call trace service. This service then passes on the information to the customer.