This TS gives the stage 2 description of Unstructured Supplementary Service Data (USSD).
The unstructured supplementary service data (USSD) mechanism allows the Mobile Station (MS) user and a PLMN
operator defined application to communicate in a way which is transparent to the MS and to intermediate network
entities. The mechanism allows development of PLMN specific supplementary services.
This TS defines the requirements for handling USSD at the MS and network entities. It does not include specification of particular applications, nor does it specify how a particular application is selected. Where more than one application exists at a network entity, routing of messages to the correct application is carried out by the USSD handler.
The MMI for USSD is specified in TS 22.030
and TS 22.090
. The alphabet indicator and the data coding scheme are
defined in TS 23.038