ASR - Average Seizure Ratio

ASR is the ratio of Successfully Connected Calls to Call Attempts. 

Usually shown as a percentage (%), the formula is:   Successful (answered) Calls / Calls attempts * 100  

The acceptable level (%) ASR depends on the type of voice traffic you put through, and your goals in terms of revenue and traffic statistics.  It is generally understood that carriers with very low ASRs (~20%) have high volumes of calls that fail, and therefore calls that consume infrastructure resources, but with no (or very little) revenue.   As such, higher ASRs generally equate to higher revenue/margins.  If you are experiencing low ASR statistics, you will generally see a low ACD (Average Call Duration) - often caused by high volumes of calls from Outbound Call Centers (See below).  Your Sippy Softswitch does not typically affect ASR

More information can be found at:
Understanding Answer Seizure Ratio (ASR)

ACD - Average Call Duration

The Average Call Duration (ACD) is the average length of all successful (answered) calls that pass through your Softswitch.  ACD may change during peak periods (such as holidays when people leave many short voicemails) or in contrast may remain constant (for example) if your customers pass a high degree of call center traffic, ACD might remain constantly low.

Usually measured in seconds, the formula for ACD is:Total duration, seconds (answered calls) / Total number of answered calls

If you are providing retail solutions, you may expect to see an ASR of 480 seconds (8 minutes), typically wholesale SIP carriers will expect to see around 300 seconds (5 minutes) whereas call centers may only expect to see 60-120 seconds (1-2 minutes).  Lower ACD traffic is generally lower profit.  Extremely low ACD is indicativesymbolic of call centers.  It may be hard to find vendors (*routes) that will accept ultra-low ACD.