For interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) or parallel automatic calling equipment (ACE).

Cross References:
ISO 261
ISO 8480
IEC 50(581)
IEC 807-2
CCITT Recommendation S.16
CCITT Recommendation V.10
CCITT Recommendation V.11
CCITT Recommendation V. 19
CCITT Recommendation V.20
CCITT Recommendation V. 21
CCITT Recommendation V.22
CCITT Recommendation V. 22 bis
CCITT Recommendation V.23
CCITT Recommendation V.24
CCITT Recommendation V.25
CCITT Recommendation V. 25 bis
CCITT Recommendation V.26
CCITT Recommendation V.26 bis
CCITT Recommendation V.26 ter
CCITT Recommendation V.27
CCITT Recommendation V.27 bis
CCITT Recommendation V.27 ter
CCITT Recommendation V.28
CCITT Recommendation V.29
CCITT Recommendation V.31
CCITT Recommendation V.31 bis
CCITT Recommendation V. 32
CCITT Recommendation V.33
CCITT Recommendation V. 35
CCITT Recommendation V.36
CCITT Recommendation V. 37
CCITT Recommendation X.20
CCITT Recommendation X. 20 bis
CCITT Recommendation X.21 bis
CCITT Recommendation X.24