The Column to the right of your 4 columns with phone numbers needs to be free to use.
Change references as required. This code is for Column C to G.
Code:
Sub Try_This()
Dim i As Long
With Range("F7:F" & Cells(Rows.Count, "F").End(xlUp).Row).Offset(, 1)
.Formula = "= ""(""&LEFT(RC[-1],3)&"")""&"" ""&MID(RC[-1],5,3)&"" ""&MID(RC[-1],9,4)"
.Value = .Value
End With
For i = 7 To Cells(Rows.Count, "F").End(xlUp).Row
If Cells(i, 7) = Cells(i, 3) And Cells(i, 7) = Cells(i, 4) And Cells(i, 7) = Cells(i, 5) Then Cells(i, 6).Value = ""
Next I
Columns("G:G").ClearContents
End Sub