Voice

Place an outbound phone call

Changed on

Dials to FROM one of your voice-enabled numbers and, on answer, bridges the callee to the number's stored forward destination, or to the per-call forwardTo override. Destinations can be your own AI voice agent (Vapi/Retell), a phone, or a SIP endpoint. An optional greeting is spoken to the callee before the bridge.

The 200 response means the call is dialing; the lifecycle continues asynchronously (track it via GET /v1/voice/calls/{id} or the call.* webhooks). Outbound calls are capped per rolling hour (429 when hit).

Idempotency: send an Idempotency-Key header to make retries safe; same key + same body replays the original response instead of dialing (and billing) a second call.

post/v1/voice/calls

Request

  • Base URL: https://zernio.com/api
  • URL: https://zernio.com/api/v1/voice/calls
  • Auth: HTTP bearer

Headers

Idempotency-Keystring

Optional client-generated unique key (e.g. a UUID) that makes retries safe. Same key + same body replays the original response; same key + different body → 422; key still processing → 409. A request cut off mid-handler (for example by a function timeout) can leave its key in progress, answering 409 until the key expires after 24 hours.

Request body

tostring required

Destination to dial, E.164 with leading +.

fromNumberstring

Which of your voice-enabled numbers to dial from. Optional when you have exactly one.

forwardTostring

Per-call agent override (tel:+E164, sip:..., or wss://...); defaults to the number's stored forward destination.

greetingstring

Spoken to the callee when they answer, before the bridge.

recordOverrideboolean

Per-call recording toggle; defaults to the number's setting.

transcribeOverrideboolean

Per-call transcription toggle; defaults to the number's setting.

transcriptionLanguage'auto' | 'en' | 'es'

'auto' derives from the callee's country; 'en'/'es' force it.

amdboolean

Answering-machine detection; defers the bridge until human vs machine is known.

voicemailDropMessagestring

Spoken to a detected machine, then hang up (implies amd). For outbound voicemail drops.

ringTimeoutSecondsinteger

Seconds to let the callee's phone ring before the call ends as no_answer. The destination carrier can end it sooner.

Response

Call originated; lifecycle continues asynchronously.

successboolean
callIdstring

Internal Call doc ID

telnyxCallControlIdstring
status'dialing'
direction'outbound'
fromstring
tostring
forwardTostring
greetingstring nullable
recordingEnabledboolean
transcriptionEnabledboolean
transcriptionLanguage'auto' | 'en' | 'es'

Changes

  • 664b218652beRevision changes
    • info

      added the new optional request property

    • info

      added the non-success response with the status

  • f8c8f34fb41aRevision changes
    • warning

      added the new account enum value to the / response property for the response status