The Payment Pages protocol is compatible with the Authorize.net SIM protocol to ensure that leading shopping carts are supported. For example, these shopping carts have been tested: Zen Cart, OsCommerce and Comersus. More details can be found in the shopping cart integration guides in the knowledge base. The Authorize.net SIM protocol is described at:
To switch to Payment Pages in most cases only the form POST-URL needs to be changed.
Authorize.net SIM is aimed primarily at credit card payments. However, Payment Pages allow Interac Online payments to be processed transparently.