How can I find duplicate values in a column and then change the value of a cell?

Excelcod,

Give this a try:

Sub ChangeOutgoingToVoicemailMacro_for_Excelcod()
    
    Const TmDtCol As String = "A"   'The column containing the Time/Date stamps
    Const TypeCol As String = "C"   'The column containing the Type
    Const StartRow As Long = 2      'The row the data starts on (not the header row)
    
    Dim rngTimes As Range: Set rngTimes = Range(TmDtCol & StartRow + 1, Cells(Rows.Count, TmDtCol).End(xlUp))
    Dim TimeCell As Range, rngVM As Range
    For Each TimeCell In rngTimes
        If TimeCell.Value = TimeCell.Offset(-1, 0).Value Then
            If rngVM Is Nothing Then
                Set rngVM = Cells(TimeCell.Row, TypeCol)
            Else
                Set rngVM = Union(rngVM, Cells(TimeCell.Row, TypeCol))
            End If
        End If
    Next TimeCell
    If Not rngVM Is Nothing Then rngVM.Replace "outgoing", "voicemail"
    
End Sub

Hope that helps,
~tigeravatar

tigeravatar, next time you're in Georgia, I owe you a beer! That's EXACTLY what I needed. Thank you so much!