Detection of data channel failure is required to supplement the eight-bit cyclic code. In case of unsatisfactory data transmission conditions a data channel failure indication should be given to the terminal for use in the error control equipment (see Rec
ITU-T Q.276-1988 history
1988ITU-T Q.276-1988 6.6 Service Dependability - Specifications of Signalling System No. 6 (Study Group XI) 2 pp