Integrations - OneInbox

What is an integration?

An integration is a third-party API key stored securely inside OneInbox.

OneInbox encrypts the key at rest
The raw key is never returned after creation
You reference integrations by id in other API calls

When to use

Integrations are entirely optional. OneInbox provides defaults for everything out of the box — LLM, STT, TTS, and phone numbers — so you can build and test without any integration at all. Add one only when you want to bring your own:

LLM — openai, shisa, and custom (via custom_websocket_url) are available out of the box, no key needed. anthropic and groq require you to bring your own API key and create an integration first.
STT — all providers (deepgram, whisper, assembly_ai, azure) are available out of the box. Add an integration only if you want usage billed to your own provider account.
TTS — all providers (cartesia, deepgram, elevenlabs, openai, shisa, minimax) are available out of the box. Add an integration only if you want usage billed to your own provider account.
Phone numbers — use a number from your own Twilio or Telnyx account instead of the OneInbox default
Email or calendar tools — send_email and schedule_calendar_event need a credential_id pointing at your Resend/SendGrid or Cal.com account

How to use

curl -X POST https://api.oneinbox.ai/v1/integrations \
  -H "Authorization: Bearer <api_key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "OpenAI Production",
    "provider": "openai",
    "api_key": "<your_provider_api_key>"
  }'

Email, telephony, and calendar providers also take a metadata object with provider-specific details:

# Email (Resend / SendGrid) — needs a verified "from" address
curl -X POST https://api.oneinbox.ai/v1/integrations \
  -H "Authorization: Bearer <api_key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Resend Email",
    "provider": "resend",
    "api_key": "<your_resend_api_key>",
    "metadata": { "from_email": "hello@yourdomain.com" }
  }'

# Twilio — needs the phone number you bought with them + SIP trunk config
curl -X POST https://api.oneinbox.ai/v1/integrations \
  -H "Authorization: Bearer <api_key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "My Twilio Account",
    "provider": "twilio",
    "api_key": "<your_twilio_auth_token>",
    "metadata": {
      "account_sid": "<your_twilio_account_sid>",
      "phone_number": "+15739693824",
      "sip_trunk": "<your_sip_trunk_domain>"
    }
  }'

# Cal.com — API key only; event_type_id is set on the tool, not the integration
curl -X POST https://api.oneinbox.ai/v1/integrations \
  -H "Authorization: Bearer <api_key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Cal.com Bookings",
    "provider": "calcom",
    "api_key": "<your_calcom_api_key>"
  }'

Resend setup

To use the send_email tool with Resend, you need two things: a Resend API key and a verified sending domain.

1 — Get your Resend API key

Go to resend.com and log in
Open API Keys in the left sidebar
Click Create API Key — give it a name like “OneInbox”
Copy the key (starts with re_)

2 — Verify your sending domain

Resend blocks email from domains you haven’t verified — sends fail with HTTP 403.

In Resend, go to Domains → Add Domain
Enter the domain you want to send from (e.g. yourdomain.com)
Resend shows you DNS records to add — typically three records:

Type	Purpose
`TXT`	SPF — tells receiving servers that Resend is allowed to send on your behalf
`CNAME`	DKIM — cryptographically signs outgoing messages to prove they’re genuine
`CNAME`	DMARC alignment (optional but recommended)

Add these records in your DNS provider (GoDaddy, Cloudflare, Route 53, etc.)
Click Verify in Resend — propagation usually takes a few minutes

You can only send from the exact domain (or a subdomain of it) that you verified. For example, verifying yourdomain.com lets you send from hello@yourdomain.com or noreply@yourdomain.com. It does not cover mail.yourdomain.com unless you verify that subdomain separately.

3 — Create the integration

Pass your verified sending address as metadata.from_email. This is the address that appears in the “From” field of every email the agent sends:

curl -X POST https://api.oneinbox.ai/v1/integrations \
  -H "Authorization: Bearer <api_key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Resend Email",
    "provider": "resend",
    "api_key": "<your_resend_api_key>",
    "metadata": { "from_email": "hello@yourdomain.com" }
  }'

Save the returned id — use it as credential_id when creating a send_email tool.

Cal.com setup

To use the schedule_calendar_event tool, you need a Cal.com API key and the ID of the event type you want the agent to book against.

What is an event type?

An event type in Cal.com is a bookable meeting — it defines the duration, availability, booking form, and confirmation settings. Examples:

Event type	Duration	Use case
Product Demo	30 min	Agent books a demo for interested leads
Discovery Call	20 min	First-touch qualification call
Onboarding	60 min	New customer setup session

Each event type has a numeric ID that you pass to OneInbox.

1 — Get your Cal.com API key

Log in to cal.com
Go to Settings → Developer → API Keys
Click Add — give it a name and copy the key

2 — Find your event type ID

From the URL: In your Cal.com dashboard, open Event Types and click Edit on the event you want. The URL contains the ID:

https://app.cal.com/event-types/123456
                                ^^^^^^
                                This is your event_type_id

From the API:

curl "https://api.cal.com/v2/event-types" \
  -H "Authorization: Bearer <your_calcom_api_key>"

The response lists all your event types with their id fields. Pick the one you want the agent to book.

3 — Configure availability

The agent can only book slots that are available in Cal.com. Before going live:

Set your working hours on the event type (e.g. Mon–Fri, 9am–5pm)
Choose a buffer time between meetings if needed
Make sure the event type is set to active (not draft)

If a caller asks for a time outside your availability, the booking fails with HTTP 400 and the agent will tell the caller that slot isn’t available.

The agent must collect the caller’s name and email during the conversation — both are required by Cal.com to complete a booking. Make sure your agent’s system prompt asks for these before attempting to schedule.

4 — Create the integration

curl -X POST https://api.oneinbox.ai/v1/integrations \
  -H "Authorization: Bearer <api_key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Cal.com Bookings",
    "provider": "calcom",
    "api_key": "<your_calcom_api_key>"
  }'

Save the returned id — use it as credential_id when creating a schedule_calendar_event tool. The event_type_id is set on the tool itself, not the integration.

If you run multiple event types (demo, discovery, onboarding), create a separate integration for each — each one points to a different event_type_id. Then create a separate schedule_calendar_event tool per integration, each with a clear description so the agent fires the right one based on what the caller asks for.

How integrations connect

Integration (optional BYOK)
        │
        ▼
LLM model with matching "provider"
        │
        ▼
Agent (llm_id) → Calls

Telephony integrations power Phone numbers via credential_id on number search/register.

Manage integrations

List all integrations

curl https://api.oneinbox.ai/v1/integrations \
  -H "Authorization: Bearer <api_key>"

Get an integration

curl https://api.oneinbox.ai/v1/integrations/<credential_id> \
  -H "Authorization: Bearer <api_key>"

The raw api_key is never returned — only the masked_key is shown.

Update an integration

Update the name, API key, metadata, or provider of an existing integration.

curl -X PATCH https://api.oneinbox.ai/v1/integrations/<credential_id> \
  -H "Authorization: Bearer <api_key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "OpenAI Updated",
    "api_key": "<new_api_key>"
  }'

Delete an integration

Permanently removes the stored credential. Any models or tools using this credential_id will lose access to the provider until you attach a new integration.

curl -X DELETE https://api.oneinbox.ai/v1/integrations/<credential_id> \
  -H "Authorization: Bearer <api_key>"

Next steps

Phone numbers — telephony integration
Voices — custom voice import
Create integration — API reference

​What is an integration?

​When to use

​How to use

​Resend setup

​1 — Get your Resend API key

​2 — Verify your sending domain

​3 — Create the integration

​Cal.com setup

​What is an event type?

​1 — Get your Cal.com API key

​2 — Find your event type ID

​3 — Configure availability

​4 — Create the integration

​How integrations connect

​Manage integrations

​List all integrations

​Get an integration

​Update an integration

​Delete an integration

​Next steps

What is an integration?

When to use

How to use

Resend setup

1 — Get your Resend API key

2 — Verify your sending domain

3 — Create the integration

Cal.com setup

What is an event type?

1 — Get your Cal.com API key

2 — Find your event type ID

3 — Configure availability

4 — Create the integration

How integrations connect

Manage integrations

List all integrations

Get an integration

Update an integration

Delete an integration

Next steps