Question: When a UE (User Equipment) is in Cell FACH state and supports both FDD (Frequency Division Duplex) and GSM (Global System for Mobile Communications), what condition(s) exempt the UE from performing GSM BSIC (Base Station Identity Code) identification or RSSI (Received Signal Strength Indicator) measurement?
Option 1: When the UE is engaged in an active voice call on either FDD or GSM.
Option 2: If E-DCH (Enhanced Dedicated Channel) resources are allocated to the UE or timer T321 is running.
Option 3: During periods of high network congestion to prioritize data transmission.
Option 4: When the UE has less than 32 GSM cells in its monitored set.
Explanation: According to radio resource management specifications, a UE supporting FDD and GSM is exempt from performing GSM BSIC identification or RSSI measurement if either E-DCH resources are allocated to it (indicating dedicated channel usage) or if timer T321 is running (associated with specific network procedures). This exemption highlights efficient resource utilization and prioritization in telecom networks.