From this it can be seen that received data cannot necessarily be descrambled correctly until at
least 20 bits have been correctly received and any pair of these bits, separated from each other by seven other bits, have differed in binary value from one
ITU-R V.35-1976 history
1976ITU-R V.35-1976 (WITHDRAWN) Wideband Modems Data Transmission at 48 Kilobits Per Second Using 60-108 kHz Group Band Circuits