The percentage of call attempts that are answered, used as a key measure of route quality and as an indicator of unusual or abusive traffic.
ASR is calculated by dividing the number of answered calls by the total number of call attempts, or seizures, over a period. It is one of the most common metrics in wholesale voice, used to compare carriers and routes and to detect when a route starts failing. Because it is computed directly from CDRs, it can be tracked continuously and broken down by customer, route, and destination.
What counts as a good ASR depends heavily on the type of traffic and the destination. Conversational business traffic tends to be answered more often than outbound campaign traffic, and international destinations vary widely. Comparing a customer against its own baseline and against similar customers is therefore more useful than applying a single network-wide threshold.
For fraud and compliance purposes, the trend matters more than the absolute number. A customer whose ASR collapses may be dialing large lists of numbers that do not answer, which is typical of robocalling, while an unusually high ASR to a premium destination can indicate traffic being answered by a machine to generate revenue.
Why it matters to carriers
ASR is a metric you already track for routing, so it is a cheap signal to reuse for fraud and compliance. Comparing each customer's ASR against its own history and its peers can surface robocall campaigns and revenue share schemes early, often before complaints or tracebacks arrive.