The ITU-T V-Series Recommendations on Data communication over the telephone network specify the protocols that govern approved modem communication standards and interfaces. Note: the bis and ter suffixes are ITU-T standard designators of successive iterations of a standard (bis and ter are derived from the Latin for "twice" and "thrice"). General standards Applies to V.1–V.9 V.1 is an ITU-T recommendation, entitled Equivalence between binary notation symbols and the significant conditions of a two-condition code. V.2 is an ITU-T recommendation, approved in November 1988, titled Power levels for data transmission over telephone lines. V.4 is an ITU-T recommendation, approved in November 1988, titled General structure of signals of International Alphabet No. 5 code for character oriented data transmission over public telephone networks. V.5 was an ITU-T recommendation, approved in November 1988, titled Standardization of data signalling rates for synchronous data transmission in the general switched telephone network. It has been withdrawn since. V.6 was an ITU-T recommendation, approved in November 1988, titled Standardization of data signalling rates for synchronous data transmission on leased telephone-type circuits. It has been withdrawn since. V.7 is an ITU-T recommendation, approved in November 1988, titled Definitions of terms concerning data communication over the telephone network. V.8 is an ITU-T recommendation, first approved in September 1994, titled Procedures for starting sessions of data transmission over the public switched telephone network. It has been superseded three times. The current version was approved in November 2000. V.8bis is an ITU-T recommendation, first approved in August 1996, titled Procedures for the identification and selection of common modes of operation between data circuit-terminating equipments (DCEs) and between data terminal equipments (DTEs) over the public switched telephone network and on leased point-to-point telephone-type circuits. It has been superseded twice. The current version was approved in November 2000. Interfaces and voiceband modems Applies to V.10–V.34 V.10 is an ITU-T recommendation, first agreed in 1976, for unbalanced electrical circuits for data communication at up to 100 kbit/s. It can interwork with V.28, provided it is not exposed to signals greater than 12 volts. Used with the 37-pin ISO 4902 connector, it is compatible with EIA RS-423. V.11 is an ITU-T recommendation, first agreed in 1976, for balanced electrical circuits for data communication at up to 10 Mbit/s. Used with the 37-pin ISO 4902 connector ("DC-37"), it is compatible with EIA-422. The 15-pin ISO 4903 connector ("DA-15") is recommended for data network interface. V.17 is