V.1 |
Defines binary 0/1 bits as space/mark line conditions |
V.2 |
Limits power levels of modems used on phone lines |
V.4 |
Sequence of bits within a character as transmitted |
V.5 |
Standard synchronous signalling rates - dialup lines |
V.6 |
Standard synchronous signalling rates - leased lines |
V.7 |
Vocabulary |
V.10 |
Unbalanced high-speed electrical interface characteristics |
V.11 |
Balanced high-speed electrical characteristics |
V.13 |
Simulated carrier control (full duplex modem used as half duplex) |
V.14 |
Asynchronous to synchronous conversion |
V.15 |
Acoustic couplers |
V.16 |
Electrocardiogram transmission on phone lines |
V.17 |
Application-specific modulation scheme for Group 3 fax(7.2,9.6,120,144) (provides 2-wire half-duplex
trellis-coded transmission at 7200, 9600, 12000, and 14400bps.) |
V.19 |
DTMF modems (low-speed parallel transmission) |
V.20 |
Parallel data transmission modems |
V.21 |
300 bps |
V.22 |
1200/600 bps FDX |
V.22bis |
2400 bps |
V.23 |
1200/75 bps (host tx 1200, rx 75, terminal tx 75, rx 1200) (Actually, V.23 can have only one channel or
the other or both, and the channels are INDEPENDENT (not necessarily inreverse directions). The setup
you've noted is typical of Prestel and other applications, but only one of many supported. V.23 also
supports 600bps in the highspeed channel-I |
V.24 |
known as EIA RS-232 in the USA [V.24 defines ONLY the functions of the circuits. EIA 232-E (which is how
the current version of the standard is designated) also defines electrical characteristics and connectors.
The 232-equivalent electrical characteristics are defined in CCITT V.28, and the equivalent connectors are
defined in ISO2110.) |
V.25 |
Automatic answering equipment and parallel automatic dialing (defines the 210011z "answer tone" that modems
send) |
V.25bis |
Serial automatic calling and answering - CCITT equiv of AT cmds) (this is the current CCITT standard for
modem control by computers via serial interface (in the USA, we use primarily the Hayes AT command set)] |
V.26 |
2400 bps 4-wire V.26bis 2400/1200 bps HDX V.26ter .2400/1200 bps FDX V-27 4800 bps 4-wire |
V.27bis |
4800/2400 bps 4-wire |
V.27ter |
4800/2400 bps FDX [V.27ter is also used in a half-duplex 2 wire mode to implement the 2400 and 4800 bps
transmission shemes in Group 3 fax] V.29 9600 bps 4-wire [V.29 is also used in a half-duplex 2-wire mode
to implement the 7200 and 9600 bps transmission schemes in Group 3 fax] |
V.31 |
(Rarely used) older electrical characteristics based on contact closure (like old teletypes) |
V.31bis |
The above, using optocouplers |
V.32 |
9600/4800 bps FDX |
V.32bis |
Ext'n of V.32; adds 7.2,120, and 144kbps ops & rapid rate renegotiation |
V.33 |
14.4 kbps [and 12000bps, for 4 wire leased lines] |
V.35 |
48 kbps 4-wire [The CCITT no longer recommends the use of V.35, since it was made obsolete by V.36.
However, many computers and other equipment still use the electrical interface specified in Appendix 2 of
V.35, and an particular ISO connector - and call it a "V.35" interface (although this is a misnomer)] |
V.36 |
48 kbps 4-wire |
V.37 |
72 kbps 4-wire [V.36 and, V.37 are not really "4-wire" modems. They are GROUP BAND modems, which means
they combine several telephone channels (not just one)!] |
V.40 |
How teletypes indicate parity errors |
V.41 |
An older, obsolete error control scheme |
V.42 |
Error-correcting procedures for modems using async-to-sync conversion (V.22, V.22bis, V.26ter, V.32,
V.32bis); defines EAPM protocol, and provides fallback to MNP4 |
V.42bis |
Lempel-Ziv-based compression scheme for use with V.42 LAPM |
V.50 |
Standard limits for transmission quality for modems |
V.51 |
Maintenance of international data circuits |
V.52 |
Apparatus for measuring distortion and error rate for data transmission |
V.53 |
Impairment limits for data circuits |
V.54 |
Loop test devices for modems |
V.55 |
Impulse noise measuring equipment |
V.56 |
Comparative testing of modems |
V.57 |
Comprehensive test set for highspeed data transmission |
V.100 |
Interconnection between PDNs and PSTNs (Public Data Networks, Public Switched Telephone Networks). |
V.110 |
ISDN terminal adaption |
V.120 |
ISDN terminal adaption with statistical multiplexing |
V.230 |
General data communications interface, layer 1 |