A method and system for forecasting telephony traffic trends on a network of a given service provider includes storing number portability records in a database. Each record contains information regarding a corresponding telephone number having been ported between service providers. First and second images of the database are obtained at first and second times. The first and second images are indicative of the records stored in the database at the first and second times. The images are compared to determine migration of the ported telephone numbers between the service providers. Movement of telephone traffic on the network of the given service provider is forecasted as a function of the determined migration of the ported telephone numbers between the service providers.