Answer call - Telnyx

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

Expected Webhooks (see callback schema below):

call.answered

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.

curl --location --request POST '/calls//actions/answer' \ --header 'Content-Type: application/json' \ --data-raw '{ "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d", "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901", "send_silence_when_idle": true, "webhook_url": "https://www.example.com/server-b/", "webhook_url_method": "POST" }'

Request

Authorization

Provide your bearer token in the

Authorization

header when making requests to protected resources.

Example:

Authorization: Bearer ********************

Path Params

call_control_id

string

required

Unique identifier and token for controlling the call

Body Params application/json

billing_group_id

string <uuid>

optional

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

Example:

f5586561-8ff0-4291-a0ac-84fe544797bd

client_state

string

optional

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

Example:

aGF2ZSBhIG5pY2UgZGF5ID1d

command_id

string

optional

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

Example:

891510ac-f3e4-11e8-af5b-de00688a4901

custom_headers

array[object (Custom SIP Header) {2}]

optional

Custom headers to be added to the SIP INVITE response.

Example:

[{"name":"head_1","value":"val_1"},{"name":"head_2","value":"val_2"}]

name

string

required

The name of the header to add.

Example:

head_1

value

string

required

The value of the header.

Example:

val_1

preferred_codecs

enum<string>

optional

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

Allowed value:

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

Example:

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

record

enum<string>

optional

Start recording automatically after an event. Disabled by default.

Allowed value:

record-from-answer

Example:

record-from-answer

record_channels

enum<string>

optional

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

Allowed values:

singledual

Default:

dual

Example:

single

record_custom_file_name

string

optional

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

>= 1 characters<= 40 characters

Example:

my_recording_file_name

record_format

enum<string>

optional

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

Allowed values:

wavmp3

Default:

mp3

Example:

wav

record_max_length

integer <int32>

optional

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).

Default:

Example:

1000

record_timeout_secs

integer <int32>

optional

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).

Default:

Example:

100

record_track

enum<string>

optional

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).

Allowed values:

bothinboundoutbound

Default:

both

Example:

outbound

record_trim

enum<string>

optional

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

Allowed value:

trim-silence

Example:

trim-silence

send_silence_when_idle

boolean

optional

Generate silence RTP packets when no transmission available.

Default:

false

Example:

true

sip_headers

array[object (SIP Header) {2}]

optional

SIP headers to be added to the SIP INVITE response. Currently only User-to-User header is supported.

Example:

[{"name":"User-to-User","value":"value"}]

name

enum<string>

required

The name of the header to add.

Allowed value:

User-to-User

Example:

User-to-User

value

string

required

The value of the header.

Example:

value

sound_modifications

object (Sound modifications)

optional

Use this field to modify sound effects, for example adjust the pitch.

Example:

{"octaves":0.1,"pitch":"0.8","semitone":-2,"track":"both"}

octaves

number <double>

optional

Adjust the pitch in octaves, values should be between -1 and 1, default 0

Example:

-0.5

pitch

number <double>

optional

Set the pitch directly, value should be > 0, default 1 (lower = lower tone)

Example:

0.8

semitone

number <double>

optional

Adjust the pitch in semitones, values should be between -14 and 14, default 0

Example:

-10

track

string

optional

The track to which the sound modifications will be applied. Accepted values are inbound or outbound

Default:

outbound

Example:

inbound

stream_bidirectional_codec

enum<string>

optional

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

Allowed values:

PCMUPCMAG722OPUSAMR-WB

Default:

PCMU

Example:

G722

stream_bidirectional_mode

enum<string>

optional

Configures method of bidirectional streaming (mp3, rtp).

Allowed values:

mp3rtp

Default:

mp3

Example:

rtp

stream_bidirectional_target_legs

enum<string>

optional

Specifies which call legs should receive the bidirectional stream audio.

Allowed values:

bothselfopposite

Default:

opposite

Example:

both

stream_codec

enum<string>

optional

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. Currently, transcoding is only supported between PCMU and PCMA codecs.

Allowed values:

PCMAPCMUdefault

Default:

default

Example:

PCMA

stream_track

enum<string>

optional

Specifies which track should be streamed.

Allowed values:

inbound_trackoutbound_trackboth_tracks

Default:

inbound_track

Example:

both_tracks

stream_url

string

optional

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

Example:

wss://www.example.com/websocket

transcription

boolean

optional

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

Default:

false

Example:

true

transcription_config

object (Transcription start request)

optional

Example:

{"client_state":"aGF2ZSBhIG5pY2UgZGF5ID1d","command_id":"891510ac-f3e4-11e8-af5b-de00688a4901","language":"en"}

client_state

string

optional

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

Example:

aGF2ZSBhIG5pY2UgZGF5ID1d

command_id

string

optional

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

Example:

891510ac-f3e4-11e8-af5b-de00688a4901

transcription_engine

enum<string>

optional

Engine to use for speech recognition. A - Google, B - Telnyx.

Allowed values:

Default:

Example:

transcription_engine_config

optional

transcription_tracks

string

optional

Indicates which leg of the call will be transcribed. Use inbound for the leg that requested the transcription, outbound for the other leg, and both for both legs of the call. Will default to inbound.

Default:

inbound

Example:

both

webhook_url

string

optional

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

Example:

https://www.example.com/server-b/

webhook_url_method

enum<string>

optional

HTTP request type used for webhook_url.

Allowed values:

POSTGET

Default:

POST

Example:

GET

Examples

Responses

🟢200OK

application/json

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

Body

data

object (Call Control Command Result With Recording ID)

optional

Example:

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

recording_id

string <uuid>

optional

The ID of the recording. Only present when the record parameter is set to record-from-answer.

Example:

d7e9c1d4-8b2a-4b8f-b3a7-9a671c9e9b0a

result

string

optional

Example:

🔴500Server Error