High-speed circuit-switched data, or HSCSD, is the next generation of circuit-switched data available for GSM mobile phone systems. It allows wireless data to be transmitted at a rate of 57.6 kilobits per second. HSCSD is available in more than 25 countries and is especially popular in Europe. It first became popular at the beginning of the 21st century, starting to appear in many European countries around the year 2000.
HSCSD is a standard that uses multiple time slots to send data at the same time, thus increasing transmission capacity. The more time slots that are used, the faster the transmission rate can be. These slots usually support a bandwidth of anywhere between 9.6 kilobits and 14.4 kilobits. HSCSD can use a maximum of four slots at a time, thus the 57.6 kilobits of total transmission rate.
This technology can be used only for data transfer applications, not voice. Due to the fact that voice transmissions always take precedence over data, there may be times when an HSCSD connection does not work as it should, because more slots are needed for voice applications. It has the advantage over some other types of protocols on GSM phones because it has a dedicated circuit-switched channel, which makes its transfers more reliable. This can be especially helpful for time sensitive transfers such as video. HSCSD also receives less interference from outside sources as compared to other protocols, making both voice and data sessions of higher quality.
However, some other protocols, such as general packet radio service (GPRS) are actually more popular over GSM networks. This is mainly a cost factor. GPRS is much more efficient than HSCSD, and therefore is used more frequently by companies building infrastructure and services. Thus, GPRS has a greater market saturation based on this cost factor alone.
Most mobile phone companies always try to maintain a market edge. Using a higher-priced phone service does not keep a company competitive, simply because those charges must be passed to the customer. The customer is going to consider each service and make a determination based not only on quality, but on price, with price often being a deciding factor. This explains why HSCSD is not as common as other protocols.