High-Speed Circuit Switched Data
A high-speed data technology for GSM networks. An alternative to GPRS.
Adopted mostly in Europe. No GSM networks in North America support HSCSD.
HSCSD is a high-speed version of CSD, the standard method of data connections before packet-based technologies such as GPRS. A CSD connection is considered a data "call". A CSD data call is very similar to a voice call, except with the voice codecs disabled. A CSD call therefore occupies the came bandwidth as a voice call.
Unlike packet-based technologies, a CSD or HSCSD data call uses the same amount of bandwidth at all times, regardless of whether data is being transmitted at any given moment.
HSCSD achieves higher speeds than CSD by aggregating several simultaneous CSD data connections.