Question: What international recommendation should the structure of MS international data numbers comply with, as applied in the home country of the mobile subscriber?
Option 1: ITU-T Recommendation X.120
Option 2: ITU-T Recommendation X.122
Option 3: ITU-T Recommendation X.123
Option 4: ITU-T Recommendation X.121
Explanation: The correct answer is ITU-T Recommendation X.121, as it specifies the data numbering plan that MS international data numbers should comply with, ensuring proper interworking and routing of data traffic in telecom networks.