< bgcolor="#FFFFFF">

    CCITT Modem Recommendations


Primer on Premises Data Communications
by Dr. Ken Schneider of Telebyte Technology

V.1 Equivalence between binary notation symbols and the significant conditions of a two-condition code.

V.2 Power levels for data transmission over telephone lines.

V.3 International Alphabet No. S.

V.4 General structure of signals of International Alphabet No. 5 code.

V.5 Standardization of data signaling rates for synchronous data transmission in the general switched telephone network.

V.6 Standardization of data signaling rates for synchronous data transmission on leased telephone-type circuits.

V.10 Electrical characteristics for unbalanced double-current interchange circuits for general use with integrated circuit equipment in the field of data communications.

V.1 1 Electrical characteristics for balanced double-current interchange circuits for general use with integrated circuit equipment in the field of data communications.

V.15 Use of acoustic coupling for data transmission.

V.16 Medical analog data transmission modems.

V.19 Modems for parallel data transmission using telephone signaling frequencies.

V.20 Parallel data transmission modems standardized for universal use in the general switched telephone network.                                                                                                                                                                                        Sovereign Grace Church Delaware
|
V.21 200-baud modem standardized for use in the general switched telephone network.

V.22 1.2 Kbps full-duplex 2-wire modem standardized for use in the general switched telephone network.

V.22 bis 2.4 Kbps full-duplex 2-wire modem standardized for use in the general switched telephone network with 1.2 Kbps fall-back.

V.23 600/1,200-baud modem standardized for use in the general switched telephone network.

V.24 List of definitions for interchange circuits between data-terminal equipment and data circuit-terminating equipment.

V.25 Automatic calling and/or answering on the general switched telephone network, including disabling or echo-suppressors on manually established calls.

V.25 bis Bit synchronous auto-dialing protocol for use over PSTN.

V.26 2.4 Kbps modem standardized for use on four-wire leased circuits.

V.26 bis 2.4 1.2 Kbps modem standardized for use in the general switched telephone network.

V.27 4.8 Kbps modem standardized for use on leased circuits

V.27 bis 4.8 Kbps modem with automatic equalizer standardized for use on leased circuits.

V.27 ter 4.8 2.4 Kbps modem standardized for use in the general switched telephone network

V.28 ELECTRICAL characteristics for unbalanced double-current interchange circuits.

V.29 9.6 Kbps modem for use on leased circuits.

V.31 Electrical characteristics for single current interchange circuits controlled by contact closure.

V.32 9.6 Kbps full-duplex 2-wire modem standardized for use in the general switched telephone network with 4.8 Kbps fall back.

V.33 14.4 Kbps full-duplex over 4-wire leased circuits.

V.35 Data transmission at 48 Kbps using 60 to 108 kHz group band circuits.

V.36 Modems for synchronous data transmission using 60-108 kHz group band circuits.

V.40 Error indication with electromechanical equipment.

V.41 Code-independent error control system.

V.42 Covers error-checking protocols for use on standard dial-up lines. This will enable error-free data transfer at speeds up to 19.2 Kbps without the need for leased lines.

V.50 Standard limits for transmission quality of data transmission.

V.51 Organization of the maintenance of international telephone type circuits used for data transmission.

V.52 Characteristics of distortion and error-rate measuring apparatus for data transmission.

V.53 Limits for maintenance of telephone-type circuits used for data transmission.

V.54 Loop test devices for modems.

V.55 Specification for an impulsive noise measuring instrument for telephone type circuits.

V.56 Comparative tests of modems for use over telephone-type circuits.

V.57 Comprehensive data test set for high data signaling rates.

TOP OF PAGE


CCITT Recommendations

X.1 International user classes of service in public networks

X.2 International user facilities in public data networks.

X.3 Packet assembly/disassembly facility in a public data network.

X.4 General structure of signals of International Alphabet No. 5 code for data transmission over public data networks

X.20 Interface between data terminal equipment and data circuit terminating equipment for start-stop transmission services on public data networks.

X.20 bis V21 -compatible interface between data terminal equipment and data circuit-terminating equipment for start-stop transmission services on public data networks.

X.21 General purpose interface between data terminal equipment and data circuit -terminating equipment for synchronous operation on public data networks.

X.21bis Use on public data networks of data terminal equipment which are designed for interacting to synchronous V-series modems.

X.24 List of definitions of interchange circuits between data terminal equipment and data circuit-terminating equipment on public data networks.

X.25 Interface between data terminal equipment and data circuit terminating equipment for terminals operating in the packet mode on public data networks.

X.26 Electrical characteristics for unbalanced double-current interchange circuits for general use with integrated circuit equipment in the field of data communications.

X.27 Electrical characteristics for unbalanced double-current interchange circuits for general use with integrated circuit equipment in the field of data communications.

X.28 DTE/DCE interface for a start-stop-mode data terminal equipment assessing the packet assembly/disassembly facility (PAD) on a public data network situated in the same country.

X.29 Procedures for exchange on control information and user data between a packet mode DTE and a packet assembly/disassembly facility (PAD).

X.30 Standardization of basic model page-printing machine in accordance with international Alphabet No. 5.

X.31 Characteristics, from the transmission point of view, at the interchange point between data terminal equipment and data circuit terminating equipment when a 200-baud start-stop data-terminal equipment in accordance with International Alphabet No. 5 is used.

X.32 Answer-back units for 200-bauds start-stop machines in accordance with International No. 5.

X.33 Standardization of an international text for the measurement of the margin of start-stop machines in accordance with International Alphabet No. 5.

X.40 Standardization of frequency-shift modulated transmission systems for the provision of telegraph and data channels by frequency division of a primary group.

X.50 Fundamental parameters of a multiplying scheme for the international interface between synchronous data networks.

X.51 Fundamental parameters of a multiplexing scheme for the international interface between synchronous data networks using 10-bit envelope structure.

X.60 Common channel signaling for synchronous data applications-data user part.

X.70 Terminal and transit control signaling system for start-stop services on international circuits between asynchronous data networks.

X.71 Decentralized terminal and transit control signalling system on international circuits between synchronous data networks.

X.75 Terminal and transit call control procedures and data transfer systems on international circuits between packet switched data networks.

X.92 Hypothetical reference connections for public synchronous data networks.

X.95 Network parameters in public data networks.

X.96 Call progress signals in public data networks.

X.121 International numbering plan for public data networks