proxy sms failure responses unchanged

lib/routes/api/accounts.js

@@ -683,7 +683,7 @@ router.post('/:sid/Messages', async(req, res) => {
       }
       if (response.statusCode !== 200) {
         logger.error({statusCode: response.statusCode}, `Non-success response returned by createMessage ${serviceUrl}`);
-        return res.sendStatus(response.statusCode);
+        return body ? res.status(response.statusCode).json(body) : res.sendStatus(response.statusCode);
       }
       res.status(201).json(body);
     });

lib/swagger/swagger.yaml

@@ -3163,6 +3163,22 @@ paths:
                     example: 2531329f-fb09-4ef7-887e-84e648214436
                   providerResponse:
                     type: string
+        480:
+          description: temporary failure
+          content:
+            application/json:
+              schema:
+                required:
+                  - sid
+                properties:
+                  sid:
+                    type: string
+                    format: uuid
+                    example: 2531329f-fb09-4ef7-887e-84e648214436
+                  message:
+                    type: string
+                  smpp_err_code:
+                    type: string
         400:
           description: bad request         
 components: