Question: In a 3GPP SAE network, when a UE makes an Emergency Call in Limited Service Mode and authentication on the UICC fails, how does the network handle confidentiality protection for RRC, NAS signaling, and user plane?
Option 1: The network selects the strongest available encryption algorithm (e.g., EEA2) for all three.
Option 2: Confidentiality protection is omitted only for RRC signaling, while NAS and user plane remain protected.
Option 3: The network selects EEA0 for confidentiality protection of NAS, RRC, and user plane, effectively omitting encryption.
Option 4: The network mandates the use of a specific, higher-level security protocol (e.g., IPSec) for all communications.
Explanation: According to the provided context, when authentication of credentials on the UICC during Emergency Calling in Limited Service Mode cannot be successfully performed, the network accomplishes the omission of confidentiality protection by selecting EEA0. This specifically applies to the confidentiality protection of NAS, RRC signaling, and user plane, indicating that no encryption (EEA0) is used for these in such scenarios.