Report call unsuccessful


I want to know if it is possible to know the reason when a call is not establish.

For example the phone is busy, not available, out of reach.
And after that display it through the serial port.

Hope you understand what I want.

Don't you have any ideia how to help me?

Is better to use AT commands or the GSM library?

If you are using a BlueVia SIM, call service won't work.

I am not using a BlueVia SIM.

How can i check call service?