The USB modem has default software with a driver for the PC to make calls and receive calls that work fine. I want to program it myself, if possible, using the Telephony API so that I have more control and can process voice data.
In addition, codeproject has an example application (http://www.codeproject.com/Articles/10994/TAPI-3-0-Application-development-using-C-NET). I tried it too. However, the code gave an error saying that the dll is too old. Change this line,
bcc = ln.CreateCall(textBox1.Text,TapiConstants.LINEADDRESSTYPE_PHONENUMBER|TapiConstants.LINEADDRESSTYPE_IPADDRESS,TapiConstants.TAPIMEDIATYPE_DATAMODEM|TapiConstants.TAPIMEDIATYPE_AUDIO);
bcc = ln.CreateCall(textBox1.Text, TapiConstants.LINEADDRESSTYPE_PHONENUMBER, TapiConstants.TAPIMEDIATYPE_AUDIO);
I was able to compile and run the application. Whenever I select a modem line and press a call, providing a number that it turns off immediately after dialing. Therefore, I have concerns whether this TAPI application has a different purpose and may not work with USB USB modems.
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