Method to improve fax transmission quality over packet based networks with high packet jitter by means of sending 'Fill' at the end of a scan line

摘要

A method and apparatus to improve fax quality when transmitting fax over packet based network with significant packet jitter or loss. In non-ECM mode, the method is based on insertion of “Fill” at the end of a data scan line and prior to the End-Of-Line (EOL) in order to maintain data transmission continuity toward a receiving fax machine. The insertion of “Fill” is applied when operating Facsimile transmission over Internet to increase the success rate for transmission of facsimile via T.38 or similar Facsimile relay protocols. The method ensures that network delay, packet jitter or loss do not result in violation of the T.30 protocol when transmitting data toward the receiving fax machine. An alternative method is also provided for ECM mode where HDLC flags are inserted instead of “Fill.”