A method for identifying new customers or recently changed telephone services is disclosed. The methodology discovers systems and methods for capturing telephone numbers that appear on the records of recent telephone calls of a communications network, which can or cannot be a network customer, and categorizing the telephone number as a known telephone number or an unknown telephone number. The methodology includes looking-up a name and address for telephone numbers, which are categorized as unknown telephone numbers, in a current directory service. A comparison can be performed using the looked-up name and address from the current directory service with names and addresses in a historical data source. If the looked-up name and address from the current directory service differ from name and address in the historical data source, the unknown telephone number is identified as a new customer or a recently changed telephone service.