问RingCentral JavaScript SDK (HTTP400-此授予类型未经授权)

EN

400 Bad Request

{
    "error": "unauthorized_client",
    "error_description": "Unauthorized for this grant type",
    "errors": [
        {
            "errorCode": "OAU-251",
            "message": "Unauthorized for this grant type"
        }
    ]
}

var SDK = require('ringcentral');
   var rcsdk = new SDK({ 
       server: SDK.server.sandbox, 
       appKey: 'appkey',
       appSecret: 'appSecret',
       redirectUri: ''
   });
   rcsdk.platform()
   .login({
       username: 'phone number', // phone number in full format
       extension: 101, // leave blank if direct number is used
       password: 'password'
   })
   .then(function(response) {
       console.log(response)
   })
   .catch(function(e) {
       console.log(e.message  || 'Server cannot authorize user');
   });