The legacy method of authorization involves submitting the Merchant ID and PIN via the API specific fields. To generate, or update, your gateway pin simply log into the OmniFund portal and navigate to Profile >> Settings >> Preferences. You can then click the "Generate new Gateway Pin" link to begin the process. NOTE: Generating a new gateway pin will invalidate any previously generated pin, whether it is in use or not. if you currently have an existing integration that uses the gateway pin method, you will need to insure that the existing integration is updated with the newly generated gateway pin. You may also consider using an API Access Key to segregate out integration implementations.
