Tracking outbound call ami originated

Hello,
I am writing a C program to control Asterisk Via Ami Interface. In particular I must call an external number and track the call to make sure if the call has been answered from the external party or it was not. I login to AMI server with “events:on” and I get all the events generated until the start of the external call. Then I am unable to track anymore until the call finish (external party hangup). Then I receive the hangup event. How can I track the status of the external call ? When (and if) the call has been answered I must send a personalized voice message using an async agi interface. The external number starts with “7” and here is the dialplan I use:

[from-internal]
exten => _7.,1,Dial(SIP/${EXTEN:1}@pstnbo,60,rM(callscript))

[macro-callscript]
exten => s,1,Wait(1)
same => n,Answer()
same => n,AGI(agi:async)

The last events I got into AMI are RTCPSent Events but I am unable to track down the status of the external call.
How can trak the outbound call down ?
Thank you very much for your help.
Regards.
Marco Bisio