The 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.

Most ISPs are digitally connected both to the Internet and to a 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.