REST Architecture
Standardized HTTP methods for configuration, phone number provisioning, and campaign management.
Enterprise AI Voice Agent API for Developers
Skip the telecom complexity. Deploy, manage, and scale intelligent phone bots through a single REST and WebSocket interface - with absolute control over routing, logic, and data extraction.
< 500ms
Round-trip audio latency
10,000+
Concurrent channels
60+
Local number markets
100+
Languages supported
Quick Answer
What is the OnDial AI Voice Agent API?
The OnDial AI Voice Agent API is a developer-focused REST and WebSocket interface for programming inbound and outbound conversational bots. It handles telecom routing, speech-to-text, natural language processing, and text-to-speech rendering, allowing engineering teams to automate enterprise phone calls and synchronize extracted data directly into custom backends.
API Overview
Built for modern software architecture
Fits cleanly into CI/CD pipelines and microservices - from number provisioning to real-time audio streaming.
Why Choose OnDial API
Enterprise control without telecom overhead
Compare our infrastructure to traditional telecom providers or basic wrapper tools - the engineering advantages are clear.
API Features
Programmable voice capabilities for every workflow
Quick Start
First request in under five minutes
Create Account
Register your developer profile in the OnDial dashboard.
Generate API Key
Open the Developers tab and generate a production secret. Copy it immediately - it is shown once.
Authentication
Include Authorization: Bearer <YOUR_API_KEY> on every request.
Make First Request
POST to /v1/calls/outbound with a destination number and agent prompt in the JSON body.
Receive Response
The server returns 201 Created with a unique call_id for the session.
Deploy Webhooks
Expose a local server, register the URL in webhook settings, and stream live call events.
Authentication and Security
Secure server-to-server access by default
All interactions with OnDial infrastructure require strict authentication.
API Keys
Standard secret keys for server-to-server authorization. Never embed them in client-side apps or public repositories.
Bearer Tokens
Format headers exactly as Authorization: Bearer sk_live_…
Content Type
Every POST, PUT, and PATCH request must include Content-Type: application/json.
OAuth 2.0
Reserved for partners building marketplace apps. Standard enterprise implementations should use API keys.
Production
https://api.ondial.ai/v1Standard billing rates
Sandbox
https://sandbox.ondial.ai/v1Free testing; audio is watermarked
URI path versioning is active on v1. Breaking changes follow a 12-month deprecation cycle with engineering contact notices.
API Endpoints
Core endpoints for agents, calls, and integrations
MethodEndpointTitleDescription
- POST
/v1/agents
Create AI Agent
Compile system prompt, voice characteristics, and behavioral rules into a reusable agent ID.
- POST
/v1/calls/config
Create Call Configuration
Draft a session without dialing - useful for pre-loading variables before outbound campaigns.
- PATCH
/v1/numbers/{number_id}
Inbound Call Routing
Bind a purchased number to a specific agent instead of a generic holding queue.
- POST
/v1/calls/outbound
Outbound Call Execution
Dial a destination in E.164 format and attach an agent when the call is answered.
- POST
/v1/calls/{call_id}/transfer
Transfer Active Call
Bridge the current session to a target SIP URI or phone number.
- POST
/v1/calls/{call_id}/hangup
End Call
Terminate the session immediately and trigger the final summary webhook.
- GET
/v1/analytics/agents/{agent_id}
Fetch Analytics
Pull historical minutes, average duration, and error rates for a time range.
- POST
/v1/webhooks
Register Webhook
Add a destination URL and subscribe to the events your system needs.
- PATCH
/v1/calls/{call_id}/voice
Update Voice Configuration
Alter speaking rate or pitch dynamically during an active call.
- PATCH
/v1/calls/{call_id}/language
Language Selection
Disable auto-detect and force a specific locale such as fr-CA.
- POST
/v1/calls/{call_id}/sync
Trigger CRM Sync
Bypass normal delay and immediately POST call data to your CRM integration.
- POST
/v1/integrations/calendar/book
Post Appointment Data
Inject extracted scheduling data into connected Google or Outlook accounts.
- GET
/v1/calls/{call_id}/qualification
Fetch Lead Qualification
Return a boolean array of which required questions the caller answered positively.
- POST
/v1/notifications
Trigger Notifications
Send SMS or email alerts to admins based on call events.
- GET
/v1/calls/{call_id}/summary
Retrieve Call Summary
Return the transcript array and an LLM-generated executive summary.
SDKs
Official packages for your stack
Skip raw HTTP when you can. Use an official OnDial SDK for your preferred language.
Python
pip package
pip install ondial-python-sdkNode.js
npm package
npm install @ondial/clientJava
Maven package
com.ondial.api (Maven Central)PHP
Composer package
composer require ondial/php-sdkGo
go get package
go get github.com/ondial/ondial-goC#
NuGet package
NuGet: OnDial client packageCode Examples
Execute an outbound call
curl -X POST https://api.ondial.ai/v1/calls/outbound \
-H "Authorization: Bearer YOUR_SECRET_KEY" \
-H "Content-Type: application/json" \
-d '{"to_number": "+1234567890", "agent_id": "ag_123xyz"}'Webhooks
Real-time call state for your architecture
Webhooks push state changes to your systems as the conversation unfolds.
Webhook Events
Critical events include call.ringing, call.answered, speech.user_started, speech.agent_responded, and call.completed.
Retry Logic
On 4xx or 5xx responses, delivery retries up to 5 times with exponential backoff across 24 hours.
Security & Validation
Every payload includes X-OnDial-Signature. Verify with HMAC SHA256 of the raw body using your webhook secret.
Voice Workflow Architecture
From speech to CRM in under 500ms
- Step 010ms0ms
User speaks into their phone.
- Step 0250ms50ms
Audio packets travel through the SIP trunk to the OnDial ingress node.
- Step 03150ms150ms
STT engine transcribes raw audio bytes into text.
- Step 04250ms250ms
Text is processed by the designated LLM using your agent system prompt.
- Step 05350ms350ms
LLM streams tokens to the TTS engine.
- Step 06450ms450ms
Synthesized audio is pushed back through the telecom trunk.
- Step 07500ms500ms
Background webhook logs the interaction and syncs data to your CRM.
Integrations
Connect voice data to your stack
Salesforce
Map custom fields via AppExchange to log activities against Leads or Contacts.
HubSpot
Automate call timeline events with embedded audio players.
Zoho
Push transcript data bi-directionally to keep support tickets updated.
Zendesk
Open tickets automatically when callers select support options.
Twilio
Bring Your Own Carrier - connect existing SIP trunks to OnDial AI logic.
Microsoft Teams
Fire Adaptive Cards into channels when high-value clients call in.
Google Calendar
OAuth into Workspace accounts so the bot can read free/busy arrays.
Slack
Route sentiment-warning notifications directly to manager channels.
Security Protocol
Hardened at every layer
Performance Metrics
Built for natural conversation at scale
- P99 latency so bots don't talk over users
- < 600ms
- Availability SLA with financially backed credits
- 99.99%
- Concurrent sessions per enterprise tenant
- 10,000+
- Media nodes across US, EU, and AP regions
- Global
P99 latency so bots don't talk over users
Availability SLA with financially backed credits
Concurrent sessions per enterprise tenant
Media nodes across US, EU, and AP regions
Industry Use Cases
Solve distinct architectural challenges by vertical
API Comparison
How OnDial compares
| Feature | OnDial API | ElevenLabs | Bland AI | Vapi | Retell AI | Deepgram |
|---|---|---|---|---|---|---|
| Core Architecture | Enterprise Voice Agent API | TTS Generation | General Calling | Voice UI | Conversational AI | STT / Audio |
| HIPAA / BAA Support | Yes (Standard) | Varies | Yes | Varies | Yes | Yes |
| WebSocket Latency | < 500ms | N/A | ~600ms | ~500ms | ~500ms | N/A |
| Direct DB/CRM Mapping | Yes (Native) | No | Limited | No | Limited | No |
| SIP Bridge Routing | Yes (Full Control) | No | Yes | Yes | Yes | No |
| Bring Your Own LLM | Yes | No | No | Yes | Yes | No |
Developer FAQ
Frequently asked questions
Common questions from teams integrating the OnDial Voice Agent API.
Yes. You can point purchased numbers to your webhooks for inbound handling, and use the /v1/calls/outbound endpoint to generate calls programmatically.
Ready to Build
Ready to build with the OnDial API?
Stop spending engineering hours on telecom plumbing. Generate sandbox keys and initiate your first programmatic call in minutes.