The answer-seizure ratio (ASR) is a measurement of network quality and call success rates. It is the percentage of answered telephone calls with respect to the total call volume. The answer-seizure ratio is defined as 100 times the ratio of answered calls, i.e. the number of seizures resulting in an answer, divided by the total number of seizures. The actual ASR calculation is based on CDRs.
An answered call is defined as an established SIP Dialog with a 200 OK final response.
A seizure (call attempt) is defined as 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 200OK.
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 will generate 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. At the same 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 contains details for Vendor X and Vendor Y. The seizure count is increased by one for both Vendor X and Vendor Y Trunk Groups. The answered call count is NOT increased for Vendor X and Vendor Y Trunk Groups.
The Relationship Performance report breaks out ASR % 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.
