This TS describes the procedures for using Unstructured Supplementary Service Data (USSD) operations
for mobile initiated MMI mode over IP Multimedia Core Network Subsystem (IMS). MMI mode is for the transparent
transport of MMI strings entered by the user to the Application Servers (AS) and for the transparent transport of text strings back to the User Equipment (UE) to be displayed for user information. Support of USSD service is optional and only applicable for an operator's Public Land Mobile Network (PLMN).
This TS is applicable to UE and AS which are intended to support USSD operations over IP Multimedia
Core Network Subsystem (IMS) in mobile initiated MMI mode.