You need to make an API call...see code below
'TAPI dialer
Private Declare Function TAPI_Make_Call _
Lib "tapi32.dll" Alias "tapiRequestMakeCall" _
(ByVal stNumber As String, ByVal stDummy1 As String, ByVal stDummy2
As String, _
ByVal stDummy3 As String) As Long
Function MakeTAPICall(PhoneNumber As String) As Long
On Error Resume Next
MakeTAPICall = TAPI_Make_Call(PhoneNumber, "", "", "")
End Function