Well, what was coming in my mind:
1. If you are in the same room, may be sound from speaker is appropriate: try Beep statement (see MSDN for further information);
2. You can add code to call on the phone: add MS Communication control 6.0 (comOne) and CommandButton to the form. Refer MSDN for further information about MSComm control. Here is the code:

private sub cmdDial_Click()
Dim strNumber As String

  strNumber = "123456"  'Replace this with your number
  comOne.CommPort = 1
  comOne.Settings = "9600,N,8,1"
  comOne.PortOpen = True
  comOne.Output = "ATDT" & strNumber & vbCr
  [something other code]
  comOne.PortOpen = False
End Sub

3. If you have PC, office application can link to application on your PC (if there are LAN or Dial-Up connection between PCs) through WinSock control. Use TCP protocol and read MSDN article "Using the WinSock control".