> ## 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.

# Telnyx WebRTC Voice SDK Authentication via JWTs

> Authenticate the Telnyx WebRTC Voice SDKs with short-lived JWT tokens. Generate, refresh, and validate tokens for secure browser and mobile clients.

# Voice SDK Authentication via JWTs

## Prerequisites

* An active telephony credential

## Create a Token

The following API request will generate a JWT.

```http theme={null}
POST /v2/telephony_credentials/:id/token HTTP/1.1
Host: api.telnyx.com
Authorization: Bearer XXX
```

This JWT is valid until:

* 24 hours after its creation or
* the parent telephony credential is expired

whichever comes first

## What a JWT Represents

A JWT is an authentication token for one telephony credential. It does not create a new SIP identity.

Best practices:

* JWTs minted from the same telephony credential still represent the same `sip_username` (`gencred...`)
* Create a separate telephony credential per device, then mint JWTs from that credential

## Immediate Login After Credential Creation

If you create a telephony credential and mint a JWT from it, wait about 5 seconds before using either the `gencred` or the JWT for login. Using them immediately after creation can fail transiently while the credential propagates.

## SDK Authentication

SDKs are authenticated with the JWT.

## Check SIP Registration Status

If you need to confirm whether the SDK is currently registered, use the underlying telephony credential's `sip_username` (`gencred...`) with the SIP Registration Status endpoint.

```http theme={null}
GET /v2/sip_registration_status?credential_type=telephony_credential&username=gencredabc123 HTTP/1.1
Host: api.telnyx.com
Authorization: Bearer XXX
```

## Limits

Currently, there exists

* No limit on count of tokens on a telephony credential,
* Nor any limit on the aggregate count of tokens on a single account.

## Additional Resources

* [JWT API Reference](https://developers.telnyx.com/docs/voice/webrtc/auth/jwt/index#create-a-token)
* [SIP Registration Status API Reference](https://developers.telnyx.com/api-reference/uac-connections/sip-registration-status)