Sign in
Call Commands

Answer call

Answer an incoming call. You must issue this command before executing subsequent commands on an incoming call.

Expected Webhooks:

  • call.answered
  • call.hold and call.unhold if the call is held/unheld
  • call.deepfake_detection.result if deepfake_detection was enabled
  • call.deepfake_detection.error if deepfake_detection was enabled and an error occurred
  • streaming.started, streaming.stopped or streaming.failed if stream_url was set

When the record parameter is set to record-from-answer, the response will include a recording_id field.

post/calls/{call_control_id}/actions/answer

Path parameters

call_control_idstring required

Unique identifier and token for controlling the call

Request body

billing_group_idstring uuid

Use this field to set the Billing Group ID for the call. Must be a valid and existing Billing Group ID.

client_statestring

Use this field to add state to every subsequent webhook. It must be a valid Base-64 encoded string.

command_idstring

Use this field to avoid duplicate commands. Telnyx will ignore any command with the same command_id for the same call_control_id.

preferred_codecs'G722,PCMU,PCMA,G729,OPUS,VP8,H264'

The list of comma-separated codecs in a preferred order for the forked media to be received.

stream_urlstring

The destination WebSocket address where the stream is going to be delivered.

stream_track'inbound_track' | 'outbound_track' | 'both_tracks'

Specifies which track should be streamed.

stream_codec'PCMU' | 'PCMA' | 'G722' | 'OPUS' | 'AMR-WB' | 'L16' | 'default'

Specifies the codec to be used for the streamed audio. When set to 'default' or when transcoding is not possible, the codec from the call will be used.

stream_bidirectional_mode'mp3' | 'rtp'

Configures method of bidirectional streaming (mp3, rtp).

stream_bidirectional_codec'PCMU' | 'PCMA' | 'G722' | 'OPUS' | 'AMR-WB' | 'L16'

Indicates codec for bidirectional streaming RTP payloads. Used only with stream_bidirectional_mode=rtp. Case sensitive.

stream_bidirectional_target_legs'both' | 'self' | 'opposite'

Specifies which call legs should receive the bidirectional stream audio.

send_silence_when_idleboolean

Generate silence RTP packets when no transmission available.

webhook_urlstring

Use this field to override the URL for which Telnyx will send subsequent webhooks to for this call.

webhook_url_method'POST' | 'GET'

HTTP request type used for webhook_url.

transcriptionboolean

Enable transcription upon call answer. The default value is false.

record'record-from-answer'

Start recording automatically after an event. Disabled by default.

record_channels'single' | 'dual'

Defines which channel should be recorded ('single' or 'dual') when record is specified.

record_format'wav' | 'mp3'

Defines the format of the recording ('wav' or 'mp3') when record is specified.

record_max_lengthinteger

Defines the maximum length for the recording in seconds when record is specified. The minimum value is 0. The maximum value is 43200. The default value is 0 (infinite).

record_timeout_secsinteger

The number of seconds that Telnyx will wait for the recording to be stopped if silence is detected when record is specified. The timer only starts when the speech is detected. Please note that call transcription is used to detect silence and the related charge will be applied. The minimum value is 0. The default value is 0 (infinite).

record_track'both' | 'inbound' | 'outbound'

The audio track to be recorded. Can be either both, inbound or outbound. If only single track is specified (inbound, outbound), channels configuration is ignored and it will be recorded as mono (single channel).

record_trim'trim-silence'

When set to trim-silence, silence will be removed from the beginning and end of the recording.

record_custom_file_namestring

The custom recording file name to be used instead of the default call_leg_id. Telnyx will still add a Unix timestamp suffix.

webhook_urlsobject

A map of event types to arrays of webhook URLs. When an event of the specified type occurs, the webhook URLs associated with that event type will be called instead of webhook_url. Events not mapped here will use the default webhook_url.

webhook_urls_method'POST' | 'GET'

HTTP request method to invoke webhook_urls.

webhook_retries_policiesobject

A map of event types to retry policies. Each retry policy contains an array of retries_ms specifying the delays between retry attempts in milliseconds. Maximum 5 retries, total delay cannot exceed 60 seconds.

Example request

{
  "assistant": {
    "id": "asst_123",
    "greeting": "Hi, I'm your assistant. How can I help?",
    "tools": [
      {
        "type": "hangup",
        "hangup": {}
      }
    ]
  },
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901",
  "webhook_url": "https://www.example.com/server-b/",
  "webhook_url_method": "POST",
  "send_silence_when_idle": true,
  "deepfake_detection": {
    "enabled": true,
    "timeout": 15,
    "rtp_timeout": 30
  }
}

Response

Successful response upon making a call control command that includes recording_id.

Example response

{
  "data": {
    "result": "ok",
    "recording_id": "d7e9c1d4-8b2a-4b8f-b3a7-9a671c9e9b0a"
  }
}

Changes

Changed in 12 of the 99 revisions of this API.1224

  • 88a6ea0927771See the full diff
    • ○

      added the new optional request property ////

      new-optional-request-property

  • d8b8159753ee4See the full diff
    • ○

      added soniox discriminator mapping keys to the /// request property

      request-property-discriminator-mapping-added

    • ○

      added soniox discriminator mapping keys to the / request property

      request-property-discriminator-mapping-added

    • ○

      added to the /// request property oneOf list

      request-property-one-of-added

    • ○

      added to the / request property oneOf list

      request-property-one-of-added

  • 1581f4d445661See the full diff
    • ○

      added the new omi-health/omi-med-stt-v1 enum value to the request property ///

      request-property-enum-value-added

  • 4596ec306e592See the full diff
    • ○

      the request property default value changed from assemblyai/universal-streaming to assemblyai/universal-3-5-pro

      request-property-default-value-changed

    • ○

      added the new assemblyai/universal-3-5-pro enum value to the request property ///

      request-property-enum-value-added

  • a6a61a29ecdd25See the full diff
    • ▲

      removed from the /// request property oneOf list

      request-property-one-of-removed

    • ▲

      removed from the / request property oneOf list

      request-property-one-of-removed

    • ○

      added Cohere discriminator mapping keys to the / request property

      request-property-discriminator-mapping-added

    • ○

      removed rime discriminator mapping keys from the /// request property

      request-property-discriminator-mapping-deleted

    • ○

      removed rime discriminator mapping keys from the / request property

      request-property-discriminator-mapping-deleted

    • ○

      added the new Cohere enum value to the request property /

      request-property-enum-value-added

    • ○

      added to the / request property oneOf list

      request-property-one-of-added

    This revision also has 34 changes that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

  • 1571b0380bd74See the full diff
    • ▲

      the / request property type changed from string to array, and format from uri to no format

      request-property-type-changed

    • ▲

      the response's body type changed from object to no type for status

      response-body-type-changed

    • ▲

      the / response's property type changed from object to no type for status

      response-property-type-changed

    • ▲

      the // response's property type changed from integer to string, and format from int32 to integer for status

      response-property-type-changed

    This revision also has 64 changes that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

  • 8f5f4e5379944See the full diff
    • ▲

      the response's body type changed from no type to object for status

      response-body-type-changed

    • ▲

      the / response's property type changed from no type to object for status

      response-property-type-changed

    • ▲

      the // response's property type changed from string to integer, and format from integer to int32 for status

      response-property-type-changed

    • ▲

      the /// response's property format changed from json-pointer to no format for status

      response-property-type-changed

    This revision also has 41 changes that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

  • 919265dc7d981See the full diff
    • ○

      added the new optional request property /

      new-optional-request-property

  • 924fbdb1e5a13See the full diff
    • ○

      added Reson8 discriminator mapping keys to the / request property

      request-property-discriminator-mapping-added

    • ○

      added the new Reson8 enum value to the request property /

      request-property-enum-value-added

    • ○

      added to the / request property oneOf list

      request-property-one-of-added

  • ce9e90fc16f33See the full diff
    • ○

      added Humain discriminator mapping keys to the / request property

      request-property-discriminator-mapping-added

    • ○

      added the new Humain enum value to the request property /

      request-property-enum-value-added

    • ○

      added to the / request property oneOf list

      request-property-one-of-added

Of the 99 revisions, 1 has no diff computed.