HSCSD is A system for data calls on GSM networks that came before packet based systems such as GPRS and EDGE.
High-Speed Circuit-Switched Data (HSCSD) is circuit-switched wireless data transmission for mobile users at data rates up to 38.4 Kbps, four times faster than the standard data rates of the Global System for Mobile (GSM) communication standard in 1999. HSCSD is comparable to the speed of many computer modems that communicate with today's fixed telephone networks.
HSCSD is an evolutionary technology on the way to Universal Mobile Telecommunications Service (UMTS).
HSCSD was never widely adopted outside Europe.