The present document contains the stage 2 service description for a High Speed Circuit Switched Data (HSCSD) on GSM. In analogy with CCITT Recommendations I.130 [6] (refer to annex A) and with reference of CCITT Recommendations VI.1 Q.65 [7] (Stage 2 of the method for characterization of services supported by an ISDN)@ the second stage of the HSCSD is defined as follows. Stage 2 identifies the functional capabilities and information flows needed to support the service as described in High Speed Circuit Switched Data (HSCSD) - Stage 1@ GSM 02.34 [9]. Furthermore@ it identifies various possible physical locations for the functional capabilities. The output of Stage 2@ which is signalling system independent@ is used as an input to Stage 3@ the design of signalling system and switching Recommendations.