When entering a phone number in Excel the leading zeros will be removed. This is because Excel is storing the phone number as a number and therefore sees the zero as irrelevant.
To keep the leading zero the number needs to be formatted as text. This problem is also encountered when entering house numbers, ID’s and any other number, which will be stored as text.
When entering such as number, type an apostrophe (‘) before entering the number and Excel will store it as text.
Excel may query your decision by displaying a warning tag. Click on the tag to see the options.
Select Ignore Error to remove the tag and the green triangle from the cell(s).