Response Reason Code: 123
Response Reason Text: This account has not been given the permissions required for this request.
Notes: The transaction request must include the API login ID associated with the payment gateway account.
This error indicates that a user's personal Login ID is being used to connect a website or billing software to the payment gateway. Personal login IDs may not be used to connect websites to Authorize.Net, for security reasons. For example, if an Account Owner, Account Administrator, Transaction Manager, or Account Analyst login ID is used for website or software implementation, this error will occur.
To resolve this issue, the API Login ID and Transaction Key will need to be generated and added to your software's configuration, so that the website or software may connect to Authorize.Net properly. The API Login ID can be obtained by following these steps:
1) Log into the Merchant Interface at https://account.authorize.net.
2) Click Settings in the main left side menu.
3) Click API Login and Transaction Key.
4) If an API login ID has already been generated, it will be visible here. If an API Login ID needs to be generated, you will want to enter the answer to your Secret Question in order to see the API Login ID.
For more information regarding Login IDs, Passwords, API Login IDs, Transaction Keys, and User Administration, please visit our online video tutorials at http://www.authorize.net/videos .
Taken and modified from: https://support.authorize.net/authkb/index?page=content&id=A598