Methods, systems, and computer programs for constructing a billing statement from detailed usage file (DUF) records received from an Incumbent Local Exchange Carrier (ILEC). A master file contains routing information associating each of a plurality of telephone numbering plan addresses plus additional telephone number digits (NPA-NXX) with a corresponding local access transport area (LATA). Telephone operator services (TOPS) assignment files are downloaded and used to edit the master file, thereby generating an enhanced master file. DUF records are downloaded. A set of enhanced DUF records is generated by filtering the downloaded DUF records. A rate table of customer price plans is applied to the set of enhanced DUF records and the enhanced master file to construct a billing statement.