RingCentral giving me error of "[OutboundFaxes]" at the time of sending FAX - api

Question

I am trying to send FAX using POSTMAN using following URL "https://platform.devtest.ringcentral.com/restapi/v1.0/account/~/extension/****88004/fax"
and I'm getting:
{
"errorCode": "CMN-408",
"message": "In order to call this API endpoint, user needs to have [OutboundFaxes] permission for requested resource.",
"errors": [
{
"errorCode": "CMN-408",
"message": "In order to call this API endpoint, user needs to have [OutboundFaxes] permission for requested resource.",
"permissionName": "OutboundFaxes"
}
],
"permissionName": "OutboundFaxes"
}

Answer 1

There was a problem in Bearer Token at the time of making Send Fax request.
Because I was using primary account details for generating Token and at the time of sending FAX I was using extensionid of extension 102 and Bearer Token was generated with Main account extension 101. That is why it was throwing [OutboundFaxes] permission error.
To send FAX with ExtensionId of extension 102 , then generate the token using subaccount 102 details instead of main account.

Answer 2

I have successfully reproduced the issue.
test case
The root cause is just what #Jack said: authorize with extension 101 then try to send the fax with extension 102.
The error message is
{ errorCode: 'CMN-408',
message: 'In order to call this API endpoint, user needs to have [OutboundFaxes] permission for requested resource.',
errors:
[ { errorCode: 'CMN-408',
message: 'In order to call this API endpoint, user needs to have [OutboundFaxes] permission for requested resource.',
permissionName: 'OutboundFaxes' } ],
permissionName: 'OutboundFaxes' }
I think the error message needs to be improved. It's very hard to figure out the root cause by reading it. I have reported this issue to RingCentral engineering team.