PROBLEM TO BE SOLVED: To provide new data communication system for performing data transfer at a rate higher than a rate realized in a conventional method, in which a regular modem is included. SOLUTION: A current maximum theoretical limit about data rate is not applicable in a new unsymmetrical structure for two communication end points. One end point is connected directly to a digital telephone network, while conventional telephone connection is used at the other end point. As a result, the problem of transfer can be ascribed to compensation for single telephone line interface and single analog local loop. A means for offering the compensation and a clock synchronization means are generated and practical implementation is enabled in the system. The new system, in which a rate up to a maximum of 64,000 bit per second is realized, has a wide application range for a field including wide band voice transmission, video transmission, networking, facsimile transmission, and remote computer access. COPYRIGHT: (C)2006,JPO&NCIPI