Hi,
403 is HTTP Code. Also you should be provided with response body having additional details like errorCode and appropriate message, e.g.:
HTTP 403
{ "errorCode" : "FeatureNotAvailable", "message" : "The requested feature is not available", "errors" : [ { "errorCode" : "MSG-242", "message" : "The requested feature is not available" } ] }
In RC logs I can see 3 different error codes for your account:
# MSG-242 //Sending SMS is not available from the number specified.
# MSG-304 //Phone number doesn't belong to extension
# MSG-240 //Specified recipient [${toPhoneNumber}] isn't an US phone number
Please advise if you still have any questions.
Thanks,
To get a list of valid SMS numbers, list your phone numbers by calling the 'account/~/extension/~/phone-number' endpoint and then filter by phone numbers with the 'SmsSender' feature.
Here is some documentation on this:
http://ringcentral-api-docs.readthedocs.io/en/latest/messages_sms-and-pager/#listing-valid-sms-sendi...
Until and unless the response code with error message is given here, it's difficult to say about the reason of the 403 error. It may be of many reasons like invalid client, invalid grant_type etc.
You need to provide the error code in the response here