> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cognigy.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Answering Machine Detection
The *Answering Machine Detection* feature can be enabled on outbound calls to provide an indication of whether a call has been answered by a person or a machine. To use this feature, provide the `amd` property in a [dial](/voice-gateway/references/verbs/dial) verb.
In this example, the Answering Machine Detection feature is activated as soon as the call is answered, and later sends a webhook to `amd` to determine if a human or a machine has answered the call.
```json theme={null}
{
"verb": "dial",
"actionHook": "dial",
"callerId": "+49XXXXXXXXXXX",
"target": [
{
"type": "phone",
"number": "+49XXXXXXXXXXX",
"trunk": "Twilio"
}
],
"amd": {
"actionHook": "amd",
"recognizer": {
"vendor": "microsoft",
"language": "en-US",
}
}
}
```
Example of a webhook payload:
```json theme={null}
{"type":"amd_human_detected"}
{"type":"amd_machine_detected","reason":"hint","hint":"call has been forwarded","language":"en-us"}
{"type":"amd_no_speech_detected"}
```
## Configuration
The following table lists the available parameters:
| Parameter | Type | Description | Required |
| ---------------------------------- | ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- |
| actionHook | string \| object | A webhook to receive an HTTP POST for AMD events. The default value is `amd`. | Yes |
| thresholdWordCount | number | The number of spoken words in a greeting that result in an `amd_machine_detected` result. The default value is `9`. | No |
| recognizer | object | Speech recognition parameters, used as per the [gather](/voice-gateway/references/verbs/gather) and [transcribe](/voice-gateway/references/verbs/transcribe) verbs. The default value is `application`. | No |
| recognizer.vendor | string | The speech recognition provider to use, for example, Google, Amazon, or Azure. The vendor determines transcription quality, supported languages, and feature availability. | Yes |
| recognizer.label | string | A custom label to identify this recognizer instance in logs or dashboards. Helpful when multiple recognizers are configured. | No |
| recognizer.language | string | The primary language code for transcription, for example, `en-US` for English, `fr-FR` for French. Determines how speech is interpreted. | No |
| recognizer.hints | array | An array of words or phrases that may appear in the audio and should be recognized more accurately. Useful for domain-specific terms, names, or technical vocabulary. | No |
| recognizer.hintsBoost | number | A numeric value specifying how strongly the recognizer should prioritize the hint words. Higher numbers give stronger emphasis, improving accuracy for key terms. | No |
| recognizer.altLanguages | array | An array of additional language codes that the recognizer can use for multilingual audio. Allows recognition of mixed-language content. | No |
| recognizer.profanityFilter | boolean | If `true`, the recognizer will automatically remove or mask profanity from the transcription output. | No |
| recognizer.interim | boolean | If `true`, returns partial transcription results as the audio is being processed. Useful for live captions or real-time feedback. | No |
| recognizer.punctuation | boolean | If `true`, punctuation marks, for example, periods or commas, are included in the transcription to improve readability. | No |
| recognizer.diarization | boolean | If `true`, enables speaker diarization, which assigns segments of the transcript to individual speakers. | No |
| recognizer.diarizationMinSpeakers | number | The minimum number of speakers expected in the audio. Helps the diarization algorithm distinguish between speakers accurately. | No |
| recognizer.diarizationMaxSpeakers | number | The maximum number of speakers expected in the audio. Prevents the algorithm from splitting speech unnecessarily. | No |
| recognizer.vad | object | Voice Activity Detection settings. Determines how the system detects when someone is speaking vs. silence, improving transcription timing and accuracy. | No |
| recognizer.fallbackVendor | string | Specifies an alternative transcription vendor to use if the primary vendor fails. Ensures reliability in critical workflows. | No |
| recognizer.fallbackLanguage | string | Language code to use for the fallback vendor. Must match a language supported by the fallback provider. | No |
| timers | object | An object containing various timeouts. | No |
| timers.noSpeechTimeoutMs | number | The time in milliseconds to wait for speech before returning `amd_no_speech_detected`. The default value is `5000`. | No |
| timers.decisionTimeoutMs | number | The time in milliseconds to wait before returning `amd_decision_timeout`. The default value is `15000`. | No |
| timers.toneTimeoutMs | number | The time in milliseconds to wait to hear a tone. The default value is `20000`. | No |
| timers.greetingCompletionTimeoutMs | number | The silence in milliseconds to wait for during greeting before returning `amd_machine_stopped_speaking`. The default value is `2000`. | No |
# Events
The payload included in the `actionHook` always contains a type property describing the event type.
Some event types may include additional properties.
| Event | Description | Additional Properties |
| ------------------------------- | -------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| amd\_human\_detected | A human is speaking. | `{reason, greeting, language}`, where:
- `reason` — a short greeting,
- `greeting` — a recognized greeting.
- `language` — a recognized language. |
| amd\_machine\_detected | A machine is speaking. | `{reason, hint, transcript, language}`, where:
- `reason` — a hint or long greeting.
- `hint` — a recognized hint.
- `transcript` — a recognized greeting.
- `language` — a recognized language. |
| amd\_no\_speech\_detected | No speech was detected. | - |
| amd\_decision\_timeout | No decision was able to be made in the time given. | - |
| amd\_machine\_stopped\_speaking | Machine has completed the greeting. | - |
| amd\_tone\_detected | A beep was detected. | - |
| amd\_error | An error has occurred. | An error message. |
| amd\_stopped | Answering Machine Detection was stopped. | - |
Multiple events can occur during a single call. For example, on a call to an answering machine, the sequence could be:
1. `amd_machine_detected`
2. `amd_tone_detected`
3. `amd_machine_stopped_speaking`
## Inbound calls
You can use Answering Machine Detection for incoming calls by adding an `amd` property in a [`config`](/voice-gateway/references/verbs/config) verb. It can be useful in situations where Voice Gateway is located behind a dialer. In these cases, the dialer initiates the outbound call and then links it to Voice Gateway via an `INVITE` request.
## More information
* [ANSWERING\_MACHINE\_DETECTION](/voice-gateway/references/events/ANSWERING_MACHINE_DETECTION)