Question: What is the primary source used to derive the identity of an HLR (Home Location Register) as specified by the HLR Id parameter?
Option 1: ITU-T Recommendation E.213
Option 2: CCITT Recommendation E.212
Option 3: 3GPP TS 23.003
Option 4: ISO/IEC 7812
Explanation: The HLR Id parameter's value is derived from the IMSI (International Mobile Subscriber Identity), which is defined in CCITT Recommendation E.212, providing the formatting and structure for IMSIs, directly influencing how HLR identities are derived.