SIM900: Command to identify if call is received (gsm shield arduino library)

Hello

I am using the SIM900 GSM module and want to identify if a call was received (established and accepted by the person who I called).

In the Open Electronics Library (Google Code Archive - Long-term storage for Google Code Project Hosting.) is only a function implemented, to determine if the call was established (ringing). The function call is:
call.CallStatus() == CALL_ACTIVE_VOICE

The AT command is:
AT+CPAS
Return command: 4
This means: Call in progress (MT is ready for commands from TA/TE, but a call is in progress)

But I can not find any AT commands to check, if the call was accepted by the person who I called. Can anybody help?
I looked in "SIM900_AT Command Manual_ V1.03".

Thank you in advance.
Felix

I do have the same problem. Did you solve it in any way? I did not find AT commands for that.
It might be that technically this is normally done by checking the sound output. otherwise i cant explain why there seems to be no method and (afaik - i am not knowledgable enough to be sure) no AT command.

is there a hardware trick to do that? do I overlook sth?

Anche io ho lo stesso problema. Nel frattempo, qualcuno ha trovato la soluzione?