Question: In a USIM application, what is the primary purpose of the EFMBDN (Mailbox Dialling Numbers) file when service n°47 is 'available'?
Option 1: To store Capability/Configuration parameters for mailbox services
Option 2: To contain dialling numbers and associated alpha-tags for various message mailboxes (e.g., Voicemail, Fax, Electronic Mail)
Option 3: To manage message waiting indication group types without requiring EFMBI
Option 4: To provide an index for extension records stored in the EFEXT6
Explanation: The correct answer is Option 2 because, when service n°47 is 'available', the EFMBDN file contains dialling numbers to access mailboxes (like Voicemail, Fax, Electronic Mail) along with possible associated alpha-tags for each supported mailbox, efficiently accessing various message types in a telecom network.