Group 1 - The article provides a step-by-step guide on how to modify personnel contact information in the Natural Person Electronic Tax Bureau withholding end, including both individual and batch modification methods [2][3][4]. - The process begins with logging into the withholding end and navigating to the personnel information collection page [2][3]. - Users can select the personnel whose contact information needs to be modified, double-click on the name, and then update the contact details such as mobile number and email address [4][5]. Group 2 - After making the necessary changes, users must save the modifications to ensure the updates are recorded [6]. - The article also outlines the option to export personnel information, allowing users to modify contact details in an Excel template before importing the updated information back into the system [7][9][11]. - Specific requirements for mobile numbers are highlighted, including the need for unique numbers for each individual and the prohibition of using invalid or shared numbers [12].