Abstract: In a telecommunications network, a method is provided for reading a desired telephone data record associated with a given telephone number from a line record database. Initially, a data processor reads data from an accessing data record stored in an index database. The accessing data record contains at least an accessing number designating a series of telephone numbers including the given telephone number, a pointer pointing to a data cluster in the line record database, and a blocking factor associated with the data cluster. The data cluster comprises a plurality of data nodes and includes all of the telephone data records associated with the series of telephone numbers designated by the accessing number. Each data node contains a number of individual telephone data records up to the blocking factor and a number of pointers each pointing to one of the number of individual telephone data records. The data processor accesses a data cluster based on the data read from the index database.