How to make tapirequestmakecall to work.
Use it like this: Declare Function tapiRequestMakeCall Lib "TAPI32.DLL" (ByVal lpszDestAddress As A String, ByVal lpszAppName As String, ByVal lpszCalledParty As String, ByVal AlpszComment As String) As Long
visit MrCrimson's website, he has a tapi helpfile there. Hope you find this useful.
I have used the help file from Mr. Crimsons site and it is helpful. You could also use lineMakeCall once you have obtained ownership to a line device.