Asterisk Answering Machine Detection (AMD)

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  • Published on Mar 1, 2026
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🔎 Asterisk AMD (Answering Machine Detection)

1.Overview

This document explains the AMD (Answering Machine Detection) feature of the Asterisk telephone system. AMD is used in outbound calls to determine whether the call is answered vy a human or an automated system (voicemail/IVR).

After a call is answered, AMD analyzes the first few seconds of the audio to draw a conclusion. This analysis takes into account factors like initial silence, the length of the greeting, the number of words detected, and the duration of each word.

In this document, the use of the AMD (Answering Machine Detection) feature together with IVR (Interactive Voice Response) flows and the required configuration steps will be explained.

⚠️ AMD is designed to be used only for outbound calls. Its use on inbound calls is not recommended and may not produce reliable results 


2.Outbound AMD + IVR Flow

AMD +IVR Flow diagram is in below:


3.AMD Usage in Outbound Calls

AMD should be activated immediately after an outbound call is answered and should be located before any IVR or agent routing. 


  • Go to Management  to IVR. Click plus +.


  • Fill the details.


  • Go to options. Fill the details. 

Managing the NOTSURE Status
The flow to follow in a NOTSURE situation should be determined according to system requirements:

  • Act like a HUMAN

  • Terminate the call

  • Route to an alternative IVR