Excel provides a special number format that lets you format a number as a phone number. For example, you can format a 10-digit number, such as 5555551234, as (555) 555-1234.
Select the cell or range of cells that you want to format.
On the Home tab, click the Dialog Box Launcher next to Number, or right click on the selected cells and select Format Cell...
In the Category box, click Special.
In the Type list, click Phone Number.