telnyx-voice-media-go

Telnyx Voice Media - Go

Installation

go get github.com/team-telnyx/telnyx-go

Setup

import (
  "context"
  "fmt"
  "os"

  "github.com/team-telnyx/telnyx-go"
  "github.com/team-telnyx/telnyx-go/option"
)

client := telnyx.NewClient(
  option.WithAPIKey(os.Getenv("TELNYX_API_KEY")),
)

All examples below assume client is already initialized as shown above.

Error Handling

All API calls can fail with network errors, rate limits (429), validation errors (422), or authentication errors (401). Always handle errors in production code:

import "errors"

result, err := client.Messages.Send(ctx, params)
if err != nil {
  var apiErr *telnyx.Error
  if errors.As(err, &apiErr) {
    switch apiErr.StatusCode {
    case 422:
      fmt.Println("Validation error — check required fields and formats")
    case 429:
      // Rate limited — wait and retry with exponential backoff
      fmt.Println("Rate limited, retrying...")
    default:
      fmt.Printf("API error %d: %s\n", apiErr.StatusCode, apiErr.Error())
    }
  } else {
    fmt.Println("Network error — check connectivity and retry")
  }
}

Common error codes: 401 invalid API key, 403 insufficient permissions, 404 resource not found, 422 validation error (check field formats), 429 rate limited (retry with exponential backoff).

Play audio URL

Play an audio file on the call. If multiple play audio commands are issued consecutively, the audio files will be placed in a queue awaiting playback. Notes:

• When overlay is enabled, target_legs is limited to self.

POST /calls/{call_control_id}/actions/playback_start

Optional: audio_type (enum: mp3, wav), audio_url (string), cache_audio (boolean), client_state (string), command_id (string), loop (string), media_name (string), overlay (boolean), playback_content (string), stop (string), target_legs (string)

	response, err := client.Calls.Actions.StartPlayback(
		context.Background(),
		"call_control_id",
		telnyx.CallActionStartPlaybackParams{
		AudioURL: "https://example.com/audio.mp3",
	},
	)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%+v\n", response.Data)

Returns: result (string)

Stop audio playback

Stop audio being played on the call. Expected Webhooks:

• call.playback.ended or call.speak.ended

POST /calls/{call_control_id}/actions/playback_stop

Optional: client_state (string), command_id (string), overlay (boolean), stop (string)

	response, err := client.Calls.Actions.StopPlayback(
		context.Background(),
		"call_control_id",
		telnyx.CallActionStopPlaybackParams{},
	)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%+v\n", response.Data)

Returns: result (string)

Record pause

Pause recording the call. Recording can be resumed via Resume recording command. Expected Webhooks:

There are no webhooks associated with this command.

POST /calls/{call_control_id}/actions/record_pause

Optional: client_state (string), command_id (string), recording_id (uuid)

	response, err := client.Calls.Actions.PauseRecording(
		context.Background(),
		"call_control_id",
		telnyx.CallActionPauseRecordingParams{},
	)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%+v\n", response.Data)

Returns: result (string)

Record resume

Resume recording the call. Expected Webhooks:

There are no webhooks associated with this command.

POST /calls/{call_control_id}/actions/record_resume

Optional: client_state (string), command_id (string), recording_id (uuid)

	response, err := client.Calls.Actions.ResumeRecording(
		context.Background(),
		"call_control_id",
		telnyx.CallActionResumeRecordingParams{},
	)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%+v\n", response.Data)

Returns: result (string)

Recording start

Start recording the call. Recording will stop on call hang-up, or can be initiated via the Stop Recording command. Expected Webhooks:

• call.recording.saved
• call.recording.transcription.saved
• call.recording.error

POST /calls/{call_control_id}/actions/record_start — Required: format, channels

Optional: client_state (string), command_id (string), custom_file_name (string), max_length (int32), play_beep (boolean), recording_track (enum: both, inbound, outbound), timeout_secs (int32), transcription (boolean), transcription_engine (enum: A, B, deepgram/nova-3), transcription_language (enum: af, af-ZA, am, am-ET, ar, ar-AE, ar-BH, ar-DZ, ar-EG, ar-IL, ar-IQ, ar-JO, ar-KW, ar-LB, ar-MA, ar-MR, ar-OM, ar-PS, ar-QA, ar-SA, ar-TN, ar-YE, as, auto_detect, az, az-AZ, ba, be, bg, bg-BG, bn, bn-BD, bn-IN, bo, br, bs, bs-BA, ca, ca-ES, cs, cs-CZ, cy, da, da-DK, de, de-AT, de-CH, de-DE, el, el-GR, en, en-AU, en-CA, en-GB, en-GH, en-HK, en-IE, en-IN, en-KE, en-NG, en-NZ, en-PH, en-PK, en-SG, en-TZ, en-US, en-ZA, es, es-419, es-AR, es-BO, es-CL, es-CO, es-CR, es-DO, es-EC, es-ES, es-GT, es-HN, es-MX, es-NI, es-PA, es-PE, es-PR, es-PY, es-SV, es-US, es-UY, es-VE, et, et-EE, eu, eu-ES, fa, fa-IR, fi, fi-FI, fil-PH, fo, fr, fr-BE, fr-CA, fr-CH, fr-FR, gl, gl-ES, gu, gu-IN, ha, haw, he, hi, hi-IN, hr, hr-HR, ht, hu, hu-HU, hy, hy-AM, id, id-ID, is, is-IS, it, it-CH, it-IT, iw-IL, ja, ja-JP, jv-ID, jw, ka, ka-GE, kk, kk-KZ, km, km-KH, kn, kn-IN, ko, ko-KR, la, lb, ln, lo, lo-LA, lt, lt-LT, lv, lv-LV, mg, mi, mk, mk-MK, ml, ml-IN, mn, mn-MN, mr, mr-IN, ms, ms-MY, mt, my, my-MM, ne, ne-NP, nl, nl-BE, nl-NL, nn, no, no-NO, oc, pa, pa-Guru-IN, pl, pl-PL, ps, pt, pt-BR, pt-PT, ro, ro-RO, ru, ru-RU, rw-RW, sa, sd, si, si-LK, sk, sk-SK, sl, sl-SI, sn, so, sq, sq-AL, sr, sr-RS, ss-latn-za, st-ZA, su, su-ID, sv, sv-SE, sw, sw-KE, sw-TZ, ta, ta-IN, ta-LK, ta-MY, ta-SG, te, te-IN, tg, th, th-TH, tk, tl, tn-latn-za, tr, tr-TR, ts-ZA, tt, uk, uk-UA, ur, ur-IN, ur-PK, uz, uz-UZ, ve-ZA, vi, vi-VN, xh-ZA, yi, yo, yue-Hant-HK, zh, zh-TW, zu-ZA), transcription_max_speaker_count (int32), transcription_min_speaker_count (int32), transcription_profanity_filter (boolean), transcription_speaker_diarization (boolean), trim (enum: trim-silence)

	response, err := client.Calls.Actions.StartRecording(
		context.Background(),
		"call_control_id",
		telnyx.CallActionStartRecordingParams{
			Channels: telnyx.CallActionStartRecordingParamsChannelsSingle,
			Format:   telnyx.CallActionStartRecordingParamsFormatWav,
		},
	)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%+v\n", response.Data)

Returns: result (string)

Recording stop

Stop recording the call. Expected Webhooks:

• call.recording.saved

POST /calls/{call_control_id}/actions/record_stop

Optional: client_state (string), command_id (string), recording_id (uuid)

	response, err := client.Calls.Actions.StopRecording(
		context.Background(),
		"call_control_id",
		telnyx.CallActionStopRecordingParams{
			StopRecordingRequest: telnyx.StopRecordingRequestParam{},
		},
	)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%+v\n", response.Data)

Returns: result (string)

Speak text

Convert text to speech and play it back on the call. If multiple speak text commands are issued consecutively, the audio files will be placed in a queue awaiting playback. Expected Webhooks:

• call.speak.started
• call.speak.ended

POST /calls/{call_control_id}/actions/speak — Required: payload, voice

Optional: client_state (string), command_id (string), language (enum: arb, cmn-CN, cy-GB, da-DK, de-DE, en-AU, en-GB, en-GB-WLS, en-IN, en-US, es-ES, es-MX, es-US, fr-CA, fr-FR, hi-IN, is-IS, it-IT, ja-JP, ko-KR, nb-NO, nl-NL, pl-PL, pt-BR, pt-PT, ro-RO, ru-RU, sv-SE, tr-TR), loop (string), payload_type (enum: text, ssml), service_level (enum: basic, premium), stop (string), target_legs (enum: self, opposite, both), voice_settings (object)

	response, err := client.Calls.Actions.Speak(
		context.Background(),
		"call_control_id",
		telnyx.CallActionSpeakParams{
			Payload: "Say this on the call",
			Voice:   "female",
		},
	)
	if err != nil {
		log.Fatal(err)
		Language: "en-US",
	}
	fmt.Printf("%+v\n", response.Data)

Returns: result (string)

---

Webhooks

Webhook Verification

Telnyx signs webhooks with Ed25519. Each request includes telnyx-signature-ed25519 and telnyx-timestamp headers. Always verify signatures in production:

// In your webhook handler:
func handleWebhook(w http.ResponseWriter, r *http.Request) {
  body, _ := io.ReadAll(r.Body)
  event, err := client.Webhooks.Unwrap(body, r.Header)
  if err != nil {
    http.Error(w, "Invalid signature", http.StatusBadRequest)
    return
  }
  // Signature valid — event is the parsed webhook payload
  fmt.Println("Received event:", event.Data.EventType)
  w.WriteHeader(http.StatusOK)
}

The following webhook events are sent to your configured webhook URL. All webhooks include telnyx-timestamp and telnyx-signature-ed25519 headers for Ed25519 signature verification. Use client.webhooks.unwrap() to verify.

Event	Description
callPlaybackEnded	Call Playback Ended
callPlaybackStarted	Call Playback Started
callRecordingError	Call Recording Error
callRecordingSaved	Call Recording Saved
callRecordingTranscriptionSaved	Call Recording Transcription Saved
callSpeakEnded	Call Speak Ended
callSpeakStarted	Call Speak Started

Webhook payload fields

callPlaybackEnded

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.playback.ended	The type of event being delivered.
data.id	uuid	Identifies the type of resource.
data.occurred_at	date-time	ISO 8601 datetime of when the event occurred.
data.payload.call_control_id	string	Call ID used to issue commands via Call Control API.
data.payload.connection_id	string	Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.call_leg_id	string	ID that is unique to the call and can be used to correlate webhook events.
data.payload.call_session_id	string	ID that is unique to the call session and can be used to correlate webhook events.
data.payload.client_state	string	State received from a command.
data.payload.media_url	string	The audio URL being played back, if audio_url has been used to start.
data.payload.media_name	string	The name of the audio media file being played back, if media_name has been used to start.
data.payload.overlay	boolean	Whether the stopped audio was in overlay mode or not.
data.payload.status	enum: file_not_found, call_hangup, unknown, cancelled, cancelled_amd, completed, failed	Reflects how command ended.
data.payload.status_detail	string	Provides details in case of failure.

callPlaybackStarted

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.playback.started	The type of event being delivered.
data.id	uuid	Identifies the type of resource.
data.occurred_at	date-time	ISO 8601 datetime of when the event occurred.
data.payload.call_control_id	string	Call ID used to issue commands via Call Control API.
data.payload.connection_id	string	Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.call_leg_id	string	ID that is unique to the call and can be used to correlate webhook events.
data.payload.call_session_id	string	ID that is unique to the call session and can be used to correlate webhook events.
data.payload.client_state	string	State received from a command.
data.payload.media_url	string	The audio URL being played back, if audio_url has been used to start.
data.payload.media_name	string	The name of the audio media file being played back, if media_name has been used to start.
data.payload.overlay	boolean	Whether the audio is going to be played in overlay mode or not.

callRecordingError

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.recording.error	The type of event being delivered.
data.id	uuid	Identifies the type of resource.
data.occurred_at	date-time	ISO 8601 datetime of when the event occurred.
data.payload.call_control_id	string	Call ID used to issue commands via Call Control API.
data.payload.connection_id	string	Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.call_leg_id	string	ID that is unique to the call and can be used to correlate webhook events.
data.payload.call_session_id	string	ID that is unique to the call session and can be used to correlate webhook events.
data.payload.client_state	string	State received from a command.
data.payload.reason	enum: Failed to authorize with storage using custom credentials, Invalid credentials json, Unsupported backend, Internal server error	Indication that there was a problem recording the call.

callRecordingSaved

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.recording.saved	The type of event being delivered.
data.id	uuid	Identifies the type of resource.
data.occurred_at	date-time	ISO 8601 datetime of when the event occurred.
data.payload.call_leg_id	string	ID that is unique to the call and can be used to correlate webhook events.
data.payload.call_session_id	string	ID that is unique to the call session and can be used to correlate webhook events.
data.payload.connection_id	string	Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.client_state	string	State received from a command.
data.payload.recording_started_at	date-time	ISO 8601 datetime of when recording started.
data.payload.recording_ended_at	date-time	ISO 8601 datetime of when recording ended.
data.payload.channels	enum: single, dual	Whether recording was recorded in single or dual channel.

callRecordingTranscriptionSaved

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.recording.transcription.saved	The type of event being delivered.
data.id	uuid	Identifies the type of resource.
data.occurred_at	date-time	ISO 8601 datetime of when the event occurred.
data.payload.call_control_id	string	Call ID used to issue commands via Call Control API.
data.payload.connection_id	string	Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.call_leg_id	string	ID that is unique to the call and can be used to correlate webhook events.
data.payload.call_session_id	string	ID that is unique to the call session and can be used to correlate webhook events.
data.payload.client_state	string	State received from a command.
data.payload.calling_party_type	enum: pstn, sip	The type of calling party connection.
data.payload.recording_id	string	ID that is unique to the recording session and can be used to correlate webhook events.
data.payload.recording_transcription_id	string	ID that is unique to the transcription process and can be used to correlate webhook events.
data.payload.status	enum: completed	The transcription status.
data.payload.transcription_text	string	The transcribed text

callSpeakEnded

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.speak.ended	The type of event being delivered.
data.id	uuid	Identifies the type of resource.
data.occurred_at	date-time	ISO 8601 datetime of when the event occurred.
data.payload.call_control_id	string	Call ID used to issue commands via Call Control API.
data.payload.connection_id	string	Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.call_leg_id	string	ID that is unique to the call and can be used to correlate webhook events.
data.payload.call_session_id	string	ID that is unique to the call session and can be used to correlate webhook events.
data.payload.client_state	string	State received from a command.
data.payload.status	enum: completed, call_hangup, cancelled_amd	Reflects how the command ended.

callSpeakStarted

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.speak.started	The type of event being delivered.
data.id	uuid	Identifies the type of resource.
data.occurred_at	date-time	ISO 8601 datetime of when the event occurred.
data.payload.call_control_id	string	Call ID used to issue commands via Call Control API.
data.payload.connection_id	string	Call Control App ID (formerly Telnyx connection ID) used in the call.
data.payload.call_leg_id	string	ID that is unique to the call and can be used to correlate webhook events.
data.payload.call_session_id	string	ID that is unique to the call session and can be used to correlate webhook events.
data.payload.client_state	string	State received from a command.