I have read through the previous posts concerning this subject, but have not found a solution that works for my project. My app settings are set to the JWT auth flow, and I have double-checked my credentials. I was able to connect to the API using those credentials with an Ajax call in node.js, but now we are pivoting to using a PHP backend to make the calls.

I have set up the JWT auth call following the steps in the developer documentation, with the RingCentral PHP SDK installed; however, whenever I run the code, it serves the OAU-251 "Unauthorized for this grant type" error. What am I missing?

Here is my code.

The time variables in the function are to be used later and are not used in the auth request; I have commented them out while testing to ensure those are not somehow causing errors in the auth portion.

I have also tried using both the encoded and unencoded version of the client_id and client_secret.

<?php



// Load required files and classes

require 'vendor/autoload.php';

use RingCentralSDKSDK;



// Load environmental file

$dotenv = DotenvDotenv::createImmutable(__DIR__);

$dotenv->load();



// Get environmental variables

$client_id = $_ENV['CLIENT_ID'];

$client_secret = $_ENV['CLIENT_SECRET'];

$rc_url = $_ENV['RC_SERVER_URL'];

$api_key = $_ENV['API_KEY'];



function dataRefresh($client_id, $client_secret, $rc_url) {



    // Set time variables for requests

    $start = substr(date("c", strtotime("- 1 minute")), 0, -9);

    $end = substr(date("c"), 0, -9);

    

    // Base 64 encode client_id and client_secret

    $encoded_id = base64_encode($client_id);

    $encoded_secret = base64_encode($client_secret);



    // JWT Authorization

    $rcsdk = new RingCentralSDKSDK( $client_id, $client_secret, $rc_url );

    $platform = $rcsdk->platform();

    $platform->login( [ "jwt" => $_ENV['RC_JWT'] ] );



    // Make access token available in scope

    $access_token = $_ENV['RC_JWT'];

    //echo $access_token;

} 



dataRefresh($client_id, $client_secret, $rc_url);