ACD (Average Call Duration)
Means the average duration of the calls routed bya a VoIP provider. It is a quality parameter given by the VoIP providers..
ASR (Answer-Seizure Ratio)
The ratio of successfully connected calls to attempted calls (also called 'Call Completion Rate'). ASRs vary by routes. A typical ASR to Pakistan is lower than that of France. Reasons for this include the quality of the network and the fact that it's less likely that a call to Pakistan will encounter a device such as an answering machine.