We detect voicemail using heuristic algorithms that are based on tone of voice, the speed of spoken words, and other factors. This detection usually takes three to five seconds with an accuracy of 60-75%, which is on par with industry standards.
You can enable answering machine detection (AMD) using our Call object with the machine_detection and machine_detection_time parameters.
To increase AMD accuracy, use asynchronous machine detection and increase the wait time using the machine_detection_time attribute, which specifies the time allotted in milliseconds to decide whether the connection is with a machine. The default value is 5,000. You can specify an integer value between 2,000 and 10,000.