circuit switched data (CSD)

The CSD (Circuit Switched Data) service is a data transmission servicein GSM networks.

This circuit-switched CSD service operates at 9.6 kbit/s and is characterized by its low bit error rate, which is achieved by special radio protocols and complex error correction. For the CSD service to work without errors, a flawless radio connection between the cell phone or radio modem and the base station is required. Radio connections that are susceptible to interference reduce the relatively low data rate and increase the probability of errors.