6.2 Functions and information flows

23.0903GPPRelease 17Stage 2TSUnstructured Supplementary Service Data (USSD)

The following text describes the handling of mobile network initiated USSD. Diagrammatic representations are as follows:

Figure 6.1 SDL, request from user at MS;

Figure 6.2 SDL, request from MS at MSC;

Figure 6.3 SDL, request from application at MSC;

Figure 6.4 SDL, request from MSC at VLR;

Figure 6.5 SDL, request from application at VLR;

Figure 6.6 SDL, request from VLR at HLR;

Figure 6.7 Information flow, no further information required;

Figure 6.8 Information flow, further information required;

Figure 6.9 Information flow for failed USSD request.