Question: Under what condition may a UE (User Equipment) send its IMEI (International Mobile Equipment Identity) or IMEISV (International Mobile Equipment Identity Software Version) to the network before NAS (Non-Access Stratum) security has been activated?
Option 1: When the network requests it in a plain text message.
Option 2: During an emergency attach procedure when the UE has no IMSI (International Mobile Subscriber Identity), no valid GUTI (Globally Unique Temporary ID), or no valid P-TMSI (Packet Temporary Mobile Subscriber Identity).
Option 3: When the UE is powering on for the first time.
Option 4: Never; NAS security must always be activated first.
Explanation: This option is correct because, during an emergency attach scenario where the UE lacks an IMSI, a valid GUTI, or a valid P-TMSI, the IMEI is included in the communication before NAS security activation. This exception highlights a balance between security protocols and the necessity of establishing connectivity in emergency situations. The other options are incorrect as they either violate stated security protocols (Option 1), are not mentioned as exceptions (Option 3), or misrepresent the conditional allowance for emergency attaches (Option 4).