I have dialed a number using tapirequestmakecall function in Excel VBA.
Declare Function tapiRequestMakeCall Lib "tapi32.dll" _
(ByVal stNumber As String, ByVal stDummy1 As String, _
ByVal stDummy2 As String, ByVal stDummy3 As String) As Long
Sub DialNumber(Number As String)
Dim lngStatus As Long