Actually in this case…the ISUP Call goes from Delhi to MUMBAI after HLR-MUMBAI Informs that the MS is SWITCHED OFF…then GMSC-MBI routes the call to announcement.
In this case the ISUP Message flow will be like
1.IAM DEL –> MUM
2.ACM MUM –> DEL
4.REL MUM –> DEL
CDR is Generated only when ANM Message is received from Remote end.During situations where you get announcements you wont receive ANM from remote end.