What is a CSV File?
CSV (Comma Separated Value) is a common file type used to import data from one software application to another, with commas separating the values in each field. These files are most commonly created by converting an Excel Spreadsheet to a CSV file.
To create a CSV in Excel, click Save As, type in a name for the new file, use the dropdown box below the name to select CSV (Comma delimited) then click Save.
Do not open the newly saved CSV as this may corrupt the information (changes should be made in the original Excel Document and the CSV recreated.)
Also in the Excel Document save the mobile number field as text. This can be done by right clicking on the column, format cells, and set to text- this way the 0 in the number will remain in the CSV