Question: In a UE's MMI procedure for Supplementary Services, what is the primary function of the 'SEND' step after entering the procedure information (e.g., `*SC*SI#`)?
Option 1: To display call progress indications on the UE.
Option 2: To transmit the entered supplementary service information to the network for processing.
Option 3: To determine the context for interpreting single character inputs (e.g., `*`).
Option 4: To store the supplementary service settings locally on the UE.
Explanation: The 'SEND' step initiates the transmission of user-entered information to the network, facilitating communication for supplementary service management, such as activation, deactivation, or interrogation.