> ## Documentation Index
> Fetch the complete documentation index at: https://docs.telli.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Getting Started with the telli API

> Start building with the telli API: authenticate with your API key, explore the endpoints, and download the OpenAPI specifications

The telli API is a REST API with JSON request and response bodies. Use it to manage contacts and contact properties, trigger and schedule calls, retrieve call results, and work with agents and phone numbers. For real-time call events, pair it with [webhooks](/webhooks).

If you would rather integrate without writing code, telli also connects to CRMs and automation platforms. See the [integrations overview](/integrations-overview).

<Tip>
  **Authentication**

  All endpoints authenticate with an API key from the telli app (Settings > Developer), sent as a bearer token:

  ```bash theme={null}
  Authorization: Bearer <your-api-key>
  ```
</Tip>

## OpenAPI specification

Every endpoint in this reference is generated from the API's OpenAPI files. Download them to generate client libraries, import the API into tools like Postman, or give coding agents machine-readable API context:

| Specification | Covers                                                                                 | Download                                                                         |
| ------------- | -------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------- |
| V2 API        | Contacts, contact properties, and agents, plus the [webhook](/webhooks) event payloads | [https://docs.telli.com/openapi-v2.json](https://docs.telli.com/openapi-v2.json) |
| V1 API        | Calls and phone numbers, plus the deprecated contact endpoints                         | [https://docs.telli.com/openapi.json](https://docs.telli.com/openapi.json)       |

Contact endpoints exist in both versions. Use V2 for new integrations, and see the [migration guide](/v2-migration-guide) if you are still on the deprecated V1 contact endpoints.

## Base URLs

| Service                         | Base URL                                               |
| ------------------------------- | ------------------------------------------------------ |
| API                             | [https://api.telli.com](https://api.telli.com)         |
| [MCP server](/integrations/mcp) | [https://mcp.telli.com/mcp](https://mcp.telli.com/mcp) |
| telli app                       | [https://app.telli.com](https://app.telli.com)         |