PollTxnVerification error codes

You may possibly encounter the following error codes using the PollTxnVerification API.
4845: The request parameters you supplied contain an unexpected value or format. 4e01: Service internal error. 4e03: Authorization failed. 4e21: Unable to send message to voice gateway for the given number. 4e38: Voice call is in progress. 4e3a: Invalid user input. 4e3b: Transaction for the supplied ID has expired.