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.

Webhook payload fields

callPlaybackEnded

callPlaybackStarted

callRecordingError

callRecordingSaved

callRecordingTranscriptionSaved

callSpeakEnded

callSpeakStarted