Question: What is the primary purpose of a Session Transfer Number (STN), as defined in telecom standards, in relation to a User Equipment's (UE) communication setup?
Option 1: To initiate a voice call over a Circuit Switched (CS) network for emergency services.
Option 2: To facilitate the transfer of a UE from one Public Land Mobile Network (PLMN) to another.
Option 3: To establish a direct data connection between two UEs on the same Public Switched Data Network (PSDN).
Option 4: To request the transfer of the media path from Packet Switched (PS) to Circuit Switched (CS) access for a UE.
Explanation: The correct answer highlights the STN's role in transferring the media path from PS to CS access as per telecom standards, crucial for scenarios requiring switching between packet and circuit switched networks for optimal communication.