The answer-seizure ratio (ASR) measures network quality and call success rates. The ASR is the number of answered calls (i.e. the number of seizures resulting in an answer) divided by the total number of seizures times 100. The actual ASR calculation is based on CDRs.
An answered call is an established SIP Dialog with a 200 OK final response.
A seizure (call attempt) is an established SIP Dialog with a final response (2xx,3xx,4xx,5xx,6xx).
For reporting purposes, call attempts from Termination Customer Trunk Groups only count towards the A Leg CDR. Termination Vendor Trunk Groups only count towards the B Leg plus the A Leg with a 200OK.
ASR = (sum of answered calls) / (sum of call attempts) * 100
Example
A SIP Invite comes in a Termination Customer (A Leg) Trunk Group, B Leg call attempt to Vendor X fails, B Leg call attempt Vendor Y fails, B Leg call attempt to Vendor Z succeeds (e.g. a SIP 200OK response is provided). This Call flow generates one A leg CDR and two B leg CDRs.
The A leg CDR contains details for the Termination Customer Trunk Group and Vendor Z Trunk Group. The seizure count is increased by one for both the Termination Customer Trunk Group and the Vendor Z Trunk Group. Because Vendor Z provided a 200OK, the answered call count also increases by one for both the Termination Customer Trunk Group and the Vendor Z Trunk Group.
The two B Leg CDRs contain details for Vendor X and Vendor Y. The seizure count increases by one for both Vendor X and Vendor Y Trunk Groups. The answered call count does NOT increase for Vendor X and Vendor Y Trunk Groups.
Network Effectiveness Ratio (NER) is similar to ASR but it does not take into account call failures due to user behavior.
The Relationship Performance report breaks out ASR % and NER % by all four Trunk Group Types.
The image below is for Termination Customer Trunk Groups. This report is further broken out by Relationship Name, Trunk Group Name, Region, and finally by Vendor Trunk Group.
