ASR/ACD

ASR - Answer-Seizure Ratio

The Answer-Seizure Ratio (ASR) is calculated by dividing the number of successfully answered calls by the total number of calls attempted, which are known as "seizures". Since busy signals and other rejections by the called number count as call failures, the calculated ASR value can vary depending on user behavior. (http://www.voip-info.org/wiki/view/ASR)

60-70% is considered a very good ASR in the VoIP world.

ACD – Average Call Duration

The Average Call Duration (ACD) is calculated by taking the sum of billable seconds (billsec) of answered calls and dividing it by the number of these answered calls.