These params need to be in the post body, not the url

grant_type=password&username=180244XXXXX&password=VeXXXXXX&extension=101"

Something like this in Node JS.

var basic = process.env.RC_CLIENT_ID + ":" + process.env.RC_CLIENT_SECRET;

var headers = {

            'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8',

            'Accept': 'application/json',

            'Authorization': 'Basic ' + Buffer.from(basic).toString('base64')

            };

var body = querystring.stringify({

              'grant_type' : 'password',

              'username' : encodeURIComponent(process.env.RC_USERNAME),

              'password' : process.env.RC_PASSWORD

            });

Thanks!!!

It Worked.

My curl failed, although it had worked previously:

curl https://platform.ringcentral.com/restapi/oauth/token -H "Accept: application/json" -H "Content-Type: application/x-www-form-urlencoded" -H "Authorization: Basic BasicNumberAsString" -d "grant_type=password&username=username&extension=101&password=password"
with the following error:

{

If you can login your account service web at https://service.ringcentral.com with exactly the same user credentials, then you should be able to log in with your code. Otherwise, the problem is described in the error message.

The error resolved when I added "+1" to my ten digit phone number username.

I had the same issue, change password from 64 characters to 16 characters then it worked.