I have got a requirement that we need to make a telephone call using ASP.NET application.
Our ASP.NET application is used in call center. Currently, they make a call to customer manually. Now, the call should go from our application by clicking the phone number link and starts recording the conversation between the agent (application user) and customer.
If you want to use phone line you should use Computer-telephony boards, for example Dialogic: http://www.dialogic.com/products/ip_enabled/ip_boards.htm They should have API, so you will be able to use it from your application.