Question: What happens to the P-TMSI signature after a successful attach or routing area update procedure?
Option 1: The P-TMSI signature is deleted.
Option 2: The P-TMSI signature is updated with a new value.
Option 3: The P-TMSI signature remains unchanged and continues to be used for authentication purposes.
Option 4: The P-TMSI signature is sent to the MS for verification.
Explanation: According to the specification, upon successful completion of an attach or routing area update procedure, the used P-TMSI signature shall be deleted. This ensures that a new P-TMSI signature can be assigned by the network in future procedures, maintaining security and authentication integrity.