titled Enhancements to Recommendation V.90, that establishes a modem standard allowing 56 kbit/s download, 48 kbit/s upload rates, and the new V.44 compression method. It is intended to succeed the V.90 standards. With V.92, PCM is used for both the upstream and downstream connections; previously 56K modems only used PCM for downstream data. Interworking with other networks Applies to V.100–V.199 V.110 is an ITU-T recommendation for using terminal adaptor functions for the connection of terminals having interfaces conforming to V-series to the ISDN. V.120 is an alternative to V.110 based on the LAPD protocol. V.150.1 is an ITU-T recommendation for using a modem over IP networks. V.152 is an ITU-T recommendation for using Voice-Band Data over IP Networks. Interface layer specifications for data communication Applies to V.200–V.249 V.230 is an ITU-T recommendation, approved in November 1988, titled General data communications interface layer 1 specification. Digital circuit modems Applies to V.400–V.499 V.300 is an ITU-T recommendation, first approved in January 1997, titled A 128 (144) kbit/s data circuit-terminating equipment standardized for use on digital point-to-point leased circuits. See also ITU-T 56 kbit/s modem Microcom Networking Protocols (MNP1 to 10) List of device bandwidths References External links ITU-T Recommendations: V Series V.35 Technical Info – Includes pinouts and history V.44 FAQ Technical information on the LZJH algorithm in use in the V.44 standard Basic handshakes & modulations – V.22, V.22bis & V.32 handshakes ITU-T V-series V-Series ITU-T V-series