V.90 Modem Software (V.90 soft modem)
GAO V.90 software module implements the V.90 ITU-T recommendation for modems that can connect at data rates of up to 56 Kbps. The standard specifies a pair of high-speed modems, one digital and the other analog, which are designed for Internet use. The V.90 Server Modem is a digital modem with a maximum bit rate of 56 Kbps transmit and 33.6 Kbps receive. The V.90 Client Modem is an analog modem with a maximum bit rate of 56 Kbps receive, 33.6 Kbps transmit.
Most ISPs are digitally connected both to the Internet and to the telephone company's central office (CO). When this is the case, there is a clear digital connection downstream from the ISP's modem to the CO's line card that serves the user and contains a digital to analog converter.http://www.gaoresearch.com/products/modemsoftware/other/v90.php