All request must set the accept and the content type headers to be application/json format.
Requests must also contain the api key or hmac authorization signature as authorization header as described in the authentication page.
Accept: application/json
Content-Type: application/json
Because some services take a little longer time to deliver, sometimes up to 1-2min. Kindly set your header property connection-timeout property to cover a period of 2-3 min to wait for response. Should in case it the response status comes back as pending, Kindly do a re-query to get the status of the transaction.