Question: In a Public Land Mobile Network (PLMN), when a User Equipment (UE) responds with 'user busy' to an incoming call, what action is taken by the PLMN regarding the call setup?
Option 1: The PLMN places the call on hold until the UE resources become available.
Option 2: The PLMN clears the call and sends a 'busy' indication back to the calling subscriber.
Option 3: The PLMN redirects the call to the UE's voicemail service without notifying the caller.
Option 4: The PLMN continuously retries the call setup for a predefined interval before taking any further action.
Explanation: When a User Equipment (UE) indicates it is 'user busy', this signifies that the subscriber's resources are currently unavailable. In response, the PLMN terminates the call setup process and informs the initiator of the call that the intended recipient is busy, ensuring efficient use of network resources and providing immediate feedback to the caller.