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

# API versions and deprecations

> Identify Telnyx API versions, follow endpoint-specific lifecycle notices, and plan migrations away from retired interfaces.

The current Telnyx REST API base URL includes the major version:

```text theme={null}
https://api.telnyx.com/v2
```

The `/v2` prefix identifies the API family. It does not imply that every product or operation has the same release lifecycle.

## Source of truth

Use these sources in order:

1. The current [API reference](/api-reference) for available operations and schemas.
2. Product guides for provisioning, lifecycle, and migration requirements.
3. [Telnyx release notes](https://telnyx.com/release-notes) or migration guides linked from the affected product documentation.
4. The [consolidated OpenAPI specification](https://raw.githubusercontent.com/team-telnyx/openapi/master/openapi/spec3.json) for machine-readable REST contracts.

## Track API changes

[Telnyx release notes](https://telnyx.com/release-notes) cover updates across all Telnyx products and services; they are not an API-only deprecation log. Filter the release notes by product, then confirm request and response contracts in the affected product guide and API reference.

* Subscribe by email from the release notes page.
* Subscribe to the [release notes RSS feed](https://telnyx.com/rss.xml) for automated update monitoring.
* Subscribe to [Telnyx Status](https://status.telnyx.com) for service incidents and scheduled maintenance. Status notifications describe operational availability, not API lifecycle changes.

## Deprecation handling

When a page or operation is marked deprecated:

1. Identify the documented replacement.
2. Compare request and response schemas rather than changing only the URL.
3. Update error handling, webhook consumers, and SDK method calls affected by the migration.
4. Test against the replacement before removing the old integration.
5. Complete migration before the announced retirement date.

Do not begin a new integration with a deprecated or legacy endpoint.

## Breaking and non-breaking changes

Additive fields and enum values can appear in API responses. Clients should ignore unknown object fields and handle unexpected enum values defensively where the language permits it. Removing operations, changing required fields, or changing field types requires explicit migration guidance.

## Other interfaces

Active product-specific protocols and retired HTTP APIs are not part of the V2 REST contract. See [Other Telnyx interfaces](/docs/development/api-fundamentals/legacy-apis) to distinguish them, and contact Support before modifying an existing integration whose lifecycle is unclear.