Business communications, made simpler
Mobile & desktop appsDevelopersNetwork status Help center

Voice API

Your logic.
Your call.
Your control.

Build voice into your application. Create and answer calls, play audio, collect input and control what happens next through the IllyVoIP API.

Explore the APISee a request

The building blocks
of a voice experience.

Use individual actions for live control or execute an ordered action chain in a single request.

Create & answer

Start outbound calls or answer incoming calls routed to Voice API Control.

View documentation

Speak & listen

Play audio, speak text and gather speech or keypad input from a caller.

View documentation

Direct the conversation

Transfer, hold, resume, send DTMF or end the call as your application requires.

View documentation

An action chain in practice

Speak.
Listen.
Build from there.

This request plays a greeting and gathers a spoken response on an existing call. Your application decides how to use the result.

Authentication
X-Api-Key
Request format
application/json
Required for this endpoint
Idempotency-Key

Replace the placeholders with your server-side credentials and a valid call-control session. Reuse an idempotency key only for an identical request.

Read the action-chain reference
Request body · JSON
POST/api/v1/voice/call-control/execute
{
  "call_control_id": "YOUR_CALL_CONTROL_ID",
  "actions": [
    {
      "type": "speak",
      "text": "Welcome to our support line."
    },
    {
      "type": "gather",
      "input": "speech",
      "prompt_text": "How can we help?",
      "speech_language": "en-US",
      "timeout_ms": 8000,
      "save_as": "request"
    }
  ]
}

Incoming calls

Your number.
Your application’s response.

Route an IllyVoIP phone number to Voice API Control. Subscribe to the ringing event, answer the eligible call, then use the returned call-control ID for subsequent actions.

Read the inbound-call guide
Phone numberVoice API Control routing
Ringing eventcall_ringing
Your applicationAnswer → control the call

Webhooks

Let call events
move your workflow.

Receive lifecycle events at your application’s endpoint. Use them to update records, track call progress or trigger the next step in your own system.

Explore webhooks
call_initiatedcall_ringingcall_answeredcall_completed

Verify signatures, acknowledge deliveries promptly and deduplicate by event ID. Delivery retries can repeat an event.

Choose how
you want to build.

Use call control for your application’s logic, and connect the other tools your voice experience needs.

Phone number APIs

Search, order and configure numbers as part of your platform’s workflow.

Explore Phone Numbers

Webphone SDK

Add browser calling to your interface with the documented SDK and short-lived token authentication.

Read the SDK documentation

AI Voice Agents

Configure an incoming assistant with knowledge and visual call flows in the portal.

Explore AI Voice Agents

Before your
first integration.

Ask our team
Is Voice API the same as a SIP trunk?+

No. SIP connectivity connects a phone system or platform. Voice API exposes call-control operations that your application can request, such as speaking text, collecting input and transferring a call.

Can it handle incoming and outgoing calls?+

Yes. The documentation includes outbound call creation and inbound answering. For incoming calls, route a phone number to Voice API Control and follow the documented ringing-event and answer flow.

Can I collect speech and keypad input?+

Yes. The gather endpoint supports speech and DTMF input. Use the endpoint documentation to choose the supported input options, language and timeout for your flow.

Can I use speech outside a live call?+

Yes. Standalone speech-to-text and text-to-speech endpoints are available in the API reference. Use those for audio-to-text or text-to-audio workflows; use Voice API gather and speak operations within a call.

How are speech features priced?+

The portal publishes current speech-to-text and text-to-speech rates. Voice API uses those rates for gather and speak operations. Review the current rates and applicable voice charges for your setup.

Where should the API key live?+

Keep customer API keys in your server-side application. Browser calling uses the Webphone SDK’s documented short-lived token flow instead of exposing an account API key.

Can I explore before connecting my application?+

The portal includes endpoint references, request examples, sample responses, an OpenAPI specification and an API Playground. Playground requests can run real operations; review the selected request before executing it.

Build the call flow
your application needs.

Start with the endpoint reference and current request examples.

Open Voice API docsTalk to our team