title: How to answer a call using gsm modem and detect key press from caller after answering a call
body: <p>I want to write code that will answer call using gsm modem and detect key press from caller after answering a call. I can answer a call using mobile modem but for edge modem it is showing 'NO CARRIER' and caller gets busy tone. Also, I want to receive call from gsm modem and detect the pressed keys from the caller's phone. I am using C#. I just need the AT commands.</p>