(Excel versions from 2007 to current)
When entering a phone number into a cell, it is faster to just type the number without the dashes or parenthesis. You can format a cell to automatically format the phone number for you.
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 3039032362, as (303) 903-2362.
Select the cell or range of cells that you want to format.
On the Home Tab, in the Number group, click the launcher arrow.
The Format Cells dialog box will open.
On the Number tab, select Special from Category and then choose Phone Number.
Enter the phone number, just enter the numbers and when you hit Enter, the formatting is done.
Want to read more about Excel’s number formatting? Read this post: Number Formatting in Excel