Neill, try this.

Sub CellToDialer()
'Here's some VBA code from John Walkenbach "Excel 2000 Power Programming
With VBA" book.
'It uses SendKeys to click the Dial button:

'   Transfers active cell contents to Dialer
'   And then dials the phone
'   Get the phone number
   CellContents = ActiveCell.Value
   If CellContents = "" Then
       MsgBox "Select a cell that contains a phone number."
       Exit Sub
   End If
'   Activate (or start) Dialer
   Appname = "Dialer"
   AppFile = "Dialer.exe"
   On Error Resume Next
   AppActivate (Appname)
   If Err <> 0 Then
       Err = 0
       TaskID = Shell(AppFile, 1)
       If Err <> 0 Then MsgBox "Can't start " & AppFile
   End If
'   Transfer cell contents to Dialer
   Application.SendKeys "%n" & CellContents, True
'   Click Dial button
   Application.SendKeys "%d"
End Sub